Many people are tempted to get store cards when they shop, but it might not be worth it for many. BankRate notes that these cards often charge higher interest rates and often have stricter terms that can end up costing you a lot more in the long run. Also, having multiple credit cards can damage your credit score - especially if you carry a balance on all of them. As a result, most people may be better off sticking to one card that they can track and pay off regularly.

From CBSNews.com:
How many times have you gone to a store and have the clerk at the counter say you can get 10 percent off your purchase if you sign up for that store's private credit card? It's pretty tempting, but you'll want to think twice before signing up. According to the folks at bankrate.com, these store credit cards charge interest rates that are substantially higher than those of a regular credit card. You also want to remember that having too many credit cards can damage your credit score. All that said, if there is a store you find yourself shopping at all the time, it may be worth it to get the card, because sometimes they offer deals such as a discount on purchases when you first sign up. And remember -- closing these credit cards can also hurt your credit score, so be careful not to do that too frequently, especially right before you apply for a car loan or mortgage.