I've heard that half the time a restarant's POS is configured to ask the waiter to enter the number written on the tip line, but the other half of the time, it'

I've heard that half the time a restarant's POS is configured to ask the waiter to enter the number written on the tip line, but the other half of the time, it's configured for the them to enter what's written on the total line. Meaning, in the first case, writing "math" means more work for the waiter, and in the latter case, you better be careful the amount you wrote on the total line is accurate.