see that's why at 15 til close there is this thingy called "exit prep" that i employed with most people oriented places i worked. at 15 til i'd close and lock all doors, remove all things related to service (ex. ingredients, chairs stacked, whatever) and begin cleanup, ignoring those that came to the door.

or gesture with hand signals "WE ARE CLOSED!!!
and continue with cleanup . at 5 til i'd disappear and at close time i'm walking out locking the door and heading home. i'd only do that if it was a dead night. now in a busy sitation (busy with no stopping from open till close.) then i'd be a little lenient. close up 15 minutes after close time.