It's not clear how that sort of thing would even help, it seems like just a trap for the unwary. If you're an honest person selling your mittens and paying your taxes without knowing you're supposed to have a cash register, you could get unlucky and get in trouble for innocuous behavior. If you're a drug dealer then you get a cash register and ring up all your drug sales as mitten sales. Or, if someone wanted to report less income, they would have a cash register and then use it to ring up less than all of the sales. Whether or not you have the cash register can't distinguish these and is correspondingly pointless.