My younger brother had a successful garage sale and netted about $900. When he went to deposit the money, the teller asked him where he got it. She wanted proof it was indeed from a sale. Said it was now required to ask.
So now instead if selling an item for $600 we say we want to be paid $599 by check and $1 in cash. Deposit the $599 and keep the cash. Instead withdrawing $600 you withdraw $599.