Sure thing, I just felt obligated to correct facts when you wrote "which is why time is rounded up to the hour, everywhere.".
There is also approach of no time zones at all, just one global time and people can set schedules as they see fit.
I remember travelling in Guatemala where locals refused to follow Daylight Savings Time, while the national bus companies followed the official policy, which I was glad to discover at last minute otherwise I would have missed my bus . Of course, I sympathized with locals because the policy is ineffective (re: claims of saving energy, etc) even in it's "origin" (high latitude countries), never mind tropical Guatemala with little seasonal light variation.
Well thank you professor for correcting this mistake. In my defense, how the hell could I have imagined that some countries or local governments or whoever decides on time zones would be dumb enough to decide to make their time zones 15, 30 or 45 minutes more or less than the next time zone right?
But as weird as it sounds, it appears you are right... So let me update my statement: ... which is why time is rounded up to the hour in the majority of cases.