Lock non school days on POS

It would be great if administration had the ability to lock on the POS that are non school days. We have had a cashier ring transactions on a non school day (Spring break). We have been told eTrition support cannot change the date of a transaction. So we either need to run a report, cancel all of the transactions and then re-ring them on the correct day or write on the report which day the transactions were supposed to be for. If we could lock dates in the POS so cashiers cannot choose non school days the problem would be solved.