I was wondering how to know if the bills were real or not without having a special pen to mark them. Well one way is to take your thumb nail and rake it over the coat of the President on the bill it should have a ripple texture to it. If it is just slick it is probably a fake bill. They also have a watermark that will show up when held up to a bright light. Maybe other can chime in and tell other things to look for also. I sure would hate to get a counterfeit $100 bill myself so you can't much blame a store for not wanting to cash them for small purchases.

