I used Stijn Nevens code (thank you Stijn) and have a little add-on to share. Rounding up, down and rounding to nearest.
update 2019-03-09 = comment Spinxz incorporated; thank you.
update 2019-12-27 = comment Bart incorporated; thank you.
Tested for date_delta of "X hours" or "X minutes" or "X seconds".
import datetime def round_time(dt=None, date_delta=datetime.timedelta(minutes=1), to='average'): """ Round a datetime object to a multiple of a timedelta dt : datetime.datetime object, default now. dateDelta : timedelta object, we round to a multiple of this, default 1 minute. from: http://stackoverflow.com/questions/3463930/how-to-round-the-minute-of-a-datetime-object-python """ round_to = date_delta.total_seconds() if dt is None: dt = datetime.now() seconds = (dt - dt.min).seconds if seconds % round_to == 0 and dt.microsecond == 0: rounding = (seconds + round_to / 2) // round_to * round_to else: if to == 'up': # // is a floor division, not a comment on following line (like in javascript): rounding = (seconds + dt.microsecond/1000000 + round_to) // round_to * round_to elif to == 'down': rounding = seconds // round_to * round_to else: rounding = (seconds + round_to / 2) // round_to * round_to return dt + datetime.timedelta(0, rounding - seconds, - dt.microsecond) # test data print(round_time(datetime.datetime(2019,11,1,14,39,00), date_delta=datetime.timedelta(seconds=30), to='up')) print(round_time(datetime.datetime(2019,11,2,14,39,00,1), date_delta=datetime.timedelta(seconds=30), to='up')) print(round_time(datetime.datetime(2019,11,3,14,39,00,776980), date_delta=datetime.timedelta(seconds=30), to='up')) print(round_time(datetime.datetime(2019,11,4,14,39,29,776980), date_delta=datetime.timedelta(seconds=30), to='up')) print(round_time(datetime.datetime(2018,11,5,14,39,00,776980), date_delta=datetime.timedelta(seconds=30), to='down')) print(round_time(datetime.datetime(2018,11,6,14,38,59,776980), date_delta=datetime.timedelta(seconds=30), to='down')) print(round_time(datetime.datetime(2017,11,7,14,39,15), date_delta=datetime.timedelta(seconds=30), to='average')) print(round_time(datetime.datetime(2017,11,8,14,39,14,999999), date_delta=datetime.timedelta(seconds=30), to='average')) print(round_time(datetime.datetime(2019,11,9,14,39,14,999999), date_delta=datetime.timedelta(seconds=30), to='up')) print(round_time(datetime.datetime(2012,12,10,23,44,59,7769),to='average')) print(round_time(datetime.datetime(2012,12,11,23,44,59,7769),to='up')) print(round_time(datetime.datetime(2010,12,12,23,44,59,7769),to='down',date_delta=datetime.timedelta(seconds=1))) print(round_time(datetime.datetime(2011,12,13,23,44,59,7769),to='up',date_delta=datetime.timedelta(seconds=1))) print(round_time(datetime.datetime(2012,12,14,23,44,59),date_delta=datetime.timedelta(hours=1),to='down')) print(round_time(datetime.datetime(2012,12,15,23,44,59),date_delta=datetime.timedelta(hours=1),to='up')) print(round_time(datetime.datetime(2012,12,16,23,44,59),date_delta=datetime.timedelta(hours=1))) print(round_time(datetime.datetime(2012,12,17,23,00,00),date_delta=datetime.timedelta(hours=1),to='down')) print(round_time(datetime.datetime(2012,12,18,23,00,00),date_delta=datetime.timedelta(hours=1),to='up')) print(round_time(datetime.datetime(2012,12,19,23,00,00),date_delta=datetime.timedelta(hours=1)))
floor(...).