Well having worked with cash in My life and now running a small business.Not sure if it is legal.I can say the shift manager is responsible for the actions of his shift.I am supposing that he feels that the shift manager should be responsible for the cash drawer.Unless of course the thief can be caught.Most businesses I know the Manager will sign for say $200 to start the shift.When he runs the register for the entire shift it will show all transactions.If the money and the register dont mix or the drawer is short the one that handles the cash is responsible.Therefore it is taken from his or her check.