Suppandi roundoff

Master: Suppandi, how much did you spend on the groceries today?
Suppandi: I spent Rs.99 and 50 paise.
Master: Why don’t you round it off to Rs.100.
Rounding off figures is very convenient.
Then one day-
Master: Suppandi, go and get me a ticket to Mumbai.
Suppandi: Yes Master.
When he came back,
Master: What time does the train leave tomorrow?
Suppandi: 4 p.m.
Then the next day-
Master: Its 4 p.m., and the train to Mumbai hasn’t arrived, I think it is late.
A passer by: No sir, the train left at 3:45.
Master: Suppandi, you told me the train is leaving at 4:00 p.m.
Suppandi: The time was 3:45 but I rounded it off to 4p.m.
Master: S..U..P..P..A..N..D..I..