Many cities and counties often put a SPLOST (Special Purpose Local Option Tax) on the ballot. Usually for roads or schools, usually voted for, usually a penny. They are for a limited time, then they may expire or be put on the ballot again. If they expire, then every price tag for every item, in every store is now wrong. And if both city and county expire at different times, you could get a nightmare of changes.

Easier to change the software at checkout for the changes rather than every price tag.