Originally Posted by StinkyPink

Such bullshit. Counterfeit only plays a very small role... They use the signs because if they happen to have more than a few customers "break" the larger bills, their till will not have enough change for the customers. For smaller stores because they don't have enough employees to have one running to the bank in the middle of a busy shift, and also the larger stores, as they regularly empty the drawer and put it in the safe so as to never have a large amount in the register at any given time... or... if they do, it may deter those casing the place, similar as a flashing light or security sticker as stated above.

This is all due to robbery, so this method actually addresses a few different things all at once. Such as a few others suggested above...