I think, purely my personal, non management opinion - if companies are going to be punitive about time card punches like that, then they have to expect that kind of cut off prior to closing time. Nobody on a time clock should EVER work off the clock, we don't work that way in the U.S.. To tell somebody they must be fully helpful and answer the phones up to the minute of closing, BUT don't clock out late or you'll get slapped - that means that either somebody who never answered that phone from Chatty Cathy at the last minute of the day and does not understand how the caller can go on and on and on drafted that rule - OR they want the employee to work for free, and the time of free labor is well in the past.
1) I can answer the phone when it rings and deal with the person on the other end with patience and forbearance, and clock out when the call is over and handled.
2) I can stop answering the phone a few minutes before TIME, and clock out on time, and keep my behind out of hot water with management or corporate.
I cannot do both.