what should we import for round off in python code example

Example 1: python round down

>>>import math
>>> math.floor(1.6)
1
>>> math.floor(2)
2
>>> math.floor(3.9)
3

Example 2: how to round to the nearest 25 python

def myround(x, prec=2, base=.05):
  return round(base * round(float(x)/base),prec)