But they're interested in other benefits, too, such as vacation, flex time, telecommuting and parental leave.

While millennials may not be all that well informed on benefits—HR professionals say they're "not particularly savvy when it comes to signing up for coverage"—that doesn't mean they aren't asking HR professionals about them.

In fact, 96.77 percent said they take benefits into account when considering job offers.

And while employers might be providing benefits packages to employees, that doesn't mean they're offering what millennials are most interested in.

And the cost of unhappy employees leaving can be high. The study cites Society for Human Resource Management figures that "direct replacement costs can reach as high as 60 percent of an employee's annual salary, with total costs associated with turnover ranging from 90 percent to 200 percent of annual salary."

With costs like this, some compromise in negotiations over salary and benefits is called for on both sides, according to the report, as well as flexibility in offerings.

And both sides—both HR and millennials—asked how they'd advise their contemporaries about the recruiting/hiring process and benefits discussions, had some very useful suggestions to make.

Below are five tips for millennials when dealing with benefits from a prospective employer, followed by five tips for HR personnel when the prospective employee is looking for a bit more than might be on offer.

5 tips for millennials when considering a prospective employer's benefits

5. "Many first-time job seekers are too concerned with their salary to worry too much about what their benefits hold. Benefits are everything."

Smart millennials know that benefits can make all the difference in a job, particularly health insurance and retirement benefits.

Without an employer's help in paying for the former, and contributions to the latter, life could end up being a whole lot more expensive.

Prospective employees who are savvy enough to look beyond the salary offer and ask what else the employer provides will have an easier time financially, both early on and down the road.

4. "Ask questions; don't settle for being unclear. If you are not happy with what is being offered, negotiate if at all possible."

Sometimes millennials hesitate to ask questions about what the benefits are or how they work.

It's important that they take the time to ask, and make sure they understand, what's on offer.

Smart HR professionals will be able to satisfy their questions and provide enough information for them to feel comfortable that they know what they'll be getting.

3. "Do your homework on benefits, know what benefits are being offered and make sure you understand what is being offered."

Millennials who take the time and trouble to research the benefits package at prospective companies will also have a better idea of what the company is like.

They'll also be able to take advantage of all the benefits on offer when the opportunities arise.

2. "Negotiate benefits! They are almost always more flexible than they make it seem. Also, if insurance options are really confusing to you, seek help."

Not all job candidates are aware that it is possible to ask for more or better benefits.

While they may not get everything they ask for, it's possible that the most important requests could be fulfilled—such as flex time or being able to work remotely.

1. "Make sure the wages are worth the benefits."

If the benefit package isn't all that great, the salary ought to make up for it—and if it doesn't, it might be time to look elsewhere.

Job candidates should consider whether they can do better buying health coverage on the marketplace instead of from an employer with an expensive offering, or how much longer it will take them to save for retirement if the employer doesn't provide matching funds to a 401(k) or other retirement plan.

5 tips for HR when a prospective employee is looking for a bit more

5. Consider changing the rules.

If a millennial job candidate with the skills you need wants flex time or more vacation time, can it be done?

If you've been trying to fill a particular position for some time, it may be more cost effective to give a little more than to keep hunting—or start hunting again if they leave after just a few months.

4. Don't forget existing workers, if you change the rules for new employees.

Older workers might end up among those looking for greener pastures if you provide new or additional benefits to a new employee but aren't willing to be as accommodating for someone who's been with the firm for some time already.

Be prepared to do some negotiating with existing employees who might not want flex time but see it as something extra that younger employees are getting that they were never offered.

3. Encourage interaction among all employees.

Getting employees to work together, so that different generations learn from each other, can be challenging; so can encouraging social interactions both inside and outside the workplace.

However, it can also mean that workers form stronger bonds and retention can be improved when workers feel more like a cohesive team.

2. Counter jobhopping with competitive benefits.

If employees are looking elsewhere because the company's benefits package isn't on a par with the competition, it's time to consider changing the benefits package.

Would you rather spend it on benefits, or on recruitment and training for new employees?

1. Negotiate.

Be flexible. While employers may feel that job candidates with the skills they need hold all the cards, that's not necessarily the case.

Give and take can work to the employer's advantage, too.