The latest thing I've noticed is that if you attempt to debit, say, $100 from an account that has only $95, it will successfully debit $95 and then the POS equipment will show that you still need to find some other way to pay the remaining balance. Used to be in this situation it would just be rejected outright.

It's more handy for gas pumps, but less transparent. It stops before your tank is completely filled, but doesn't say why. You can hear the difference if you are standing there while it fills, of course, but other than that you may be confused why it slowed down and stopped exactly at a certain amount and won't go any farther.