America should only use 10¢, 20¢, and 50¢ coins. Also, the dime should be enlarged (it's so frustratingly tiny!). Although I acknowledge that the U.S. would probably be better off using $1 coins rather than bills, I hate having my wallet weighed down by coins, so I'd rather keep the bills. $1 bills facilitate exchange well enough, and they cost much less to make than they're worth.