We use the X report first for closing the store at night. It tallies up all the sales in each tender type and it will give you a glance on which tender types were not tallied correctly in register countdown. You can go back in and change the register count down if an area is off.
A Z report is finalized, it does the same as the X report but you cannot change the closing tallies with the Z report after it has been run.
A ZZ report tallies for an extended reporting period.