"Join me in the cash revolution and you too can avoid credit card fraud..."
I was thinking along the same lines, but then you get cashiers making change, and sometimes that is very entertaining/frustrating, depending on your mood.
A few weeks back I was due 77 cents in change on a purchase. The cashier pulled ten dimes, a nickel and two pennies. I asked her if I could get the three quarters (that bin was full in the cash drawer) and two pennies instead, and I could tell by the blank look on her face she wasn't able to compute that as the same value. Or the kid who told me two quarters was worth 30 cents "because two quarters in football is 30 minutes."