Shoppers who want to open a store credit card to save a few bucks on new jeans should think again, because that decision could cost thousands later on when they get a mortgage. YNN's Tara Lynn Wagner filed the following report.

It's become a common exchange at cash registers around the country, as employees offer discounts to shoppers to entice them to open a store credit card. The discounts can be tempting, but Tracy Becker, president of the credit restoration company North Shore Advisory, urges consumers to reconsider.

"That 30 percent off on the suit you're buying may cost you $500 a month on your mortgage," says Becker.

That may sound like a big leap, but it's really not. Becker, the author of the book "Credit Score Power," says people do not realize that every time they apply for credit, their credit score takes a hit.

"Let's say you're 744, and you go and increase a limit or apply for a credit card. Just the fact that you applied is going to drop your score and you're going to be under that threshold that would have gotten that great interest rate," says Becker.

That threshold, she says, is over 740. Anything less is likely to cost a consumer a lot more. If someone is looking to buy a $600,000 home with a score above 740, Becker says that person could get a mortgage that costs $3,000 a month.

"If your score was a 720, you might pay $500 more a month, which is almost $170,000 more over the course of the life of the loan. That's huge," says Becker.

The type of inquiry that is done when one applies for new credit, like a store card, is called a "hard pull." Each pull will knock five points off a credit score for about six months.

However, there is an exception when it comes to getting a mortgage. Rather than hold each individual inquiry against the consumer, he or she gets a window of time to apply with several different lenders to see who has the best rate.

"Within a 14-day window, you can go to 20,000 different banks and it's considered one inquiry and will only drop your score five points," Becker says.

The first step toward increasing a credit score, according to Becker, is knowing what it is. Two of the three scores can be purchased at myfico.com, and the cost — roughly $20 per number — could be money well spent.

"It's well worth the investment if you're going to find out what your credit is," Becker says.