Human Nature

I realize that it's a good policy for stores to have one of those devices that check paper money to see if they are fake, but it seemed odd to me when I paid for my purchase with a five-dollar-bill and 11 cents, that being exact change, that the cashier checked the bill, both sides, and then two of them conferred together before they accepted it. It would seem to me, that if I were going to defraud them of the $5.11 of goods, that I would give them a much larger bill, $20 or more likely a $50, so that I could get the real government currency for the fake bill. Or perhaps I am not a very intelligent fraud artist. It kind of irked me.