You’re scanning the shelves at a local pharmacy, grocery, or convenience store, and your eyes land on a sales tag. At first glance, it looks like you can get a product for a deep discount. But take a closer look. Will you get a discount today? Or will you have to pay the full price today and get money off a future purchase?

Keep an eye out for creative math on store tags and weekly ads. It might look something like this:

In this case, you’re not really getting this product for $2. You have to pay $5 at the register today — and then you’ll get a $3 discount off of something else you buy in the future. That is if you remember to use your points — or bring and use your coupon or gift card — before they expire.

We’ve long told businesses they shouldn’t obscure important terms — of course, that includes the price. Still, as a shopper, it pays to take a moment to review and understand the offer. If you find that a retailer is hiding important facts about the price, you can take your business elsewhere.