round() is Python's built-in function for rounding numbers. It uses "round half to even" (also known as bankers' rounding), meaning numbers ending in .5 are rounded to the nearest even integer. For example:

• round(2.5) → 2

• round(3.5) → 4

To round to a specific number of decimal places, pass the desired number as the second argument:

• round(3.14159, 2) → 3.14

For rounding up to the nearest integer, use math.ceil():

• import math; math.ceil(3.2) → 4

For rounding down, use math.floor():

• import math; math.floor(3.7) → 3

To round up to a specific decimal place, combine multiplication, math.ceil(), and division:

import math
def round_up(num, dec=0):
    mult = 10 ** dec
    return math.ceil(num * mult) / mult
round_up(2.543, 2)  # → 2.55

The math module provides ceil(), floor(), and trunc() for precise control over rounding behavior.