I agree that the cashiers don't always know if the card will scan or not. If you have one, always try it. Of course, it is considered a coupon in one sense of a way if you are trying to use it with a single purchase, i.e., using a 40% coupon. That's not going to fly but I usually have several items and the computer will figure out where the discount goes. The savings is usually about the amount of taxes.