I've had no problems giving change with dollars (even when a total is something like 18.03 and I give $20.05) so I think everyone around here has seen that. But a few years back when I used to pay with a check, I wrote one check for $10 over the total so I could get some cash and the cashier had to get the calculator out to figure my change.
I knew someone from New Mexico who tried to order something over the phone only to be told the company only ships to the United States. Then they would not believe her that New Mexico IS part of the United States.