It seems easier to use the ceiling

From looking at the bottom of the linked post (which says it was edited, not sure when in relation to your comment), it sounds like they wanted something that worked across arbitrary times split across units (hour/minute/seconds) without having to handle carry-over. I'm not sure I would choose to alter the times themselves over making the math a bit more complex, but the author has obviously thought about this a lot more than me, and it's nice that they at least considered that alternative.