from datetime import datetime

now = datetime.now()

def rounder(t):
    h = t.hour
    if t.minute >= 30:
        return t.replace(minute=0, hour=h+1)
    else:
        return t.replace(minute=0)

now           # 2018-02-22 22:03:53.831589
rounder(now)  # 2018-02-22 22:00:53.831589