Round up to Second Decimal Place in Python

Question

How can I round up a number to the second decimal place in python? For example:

0.022499999999999999

Should round up to 0.03<

Answer 1

Updated answer:
The problem with my original answer, as pointed out in the comments by @jpm, is the behavior at the boundaries. Python 3 makes this even more difficult since it uses "bankers" rounding instead of "old school" rounding. However, in looking into this issue I discovered an even better solution using the decimal library.

import decimal

def round_up(x, place=0):
    context = decimal.getcontext()
    # get the original setting so we can put it back when we're done
    original_rounding = context.rounding
    # change context to act like ceil()
    context.rounding = decimal.ROUND_CEILING

    rounded = round(decimal.Decimal(str(x)), place)
    context.rounding = original_rounding
    return float(rounded)

Or if you really just want a one-liner:

import decimal
decimal.getcontext().rounding = decimal.ROUND_CEILING

# here's the one-liner
float(round(decimal.Decimal(str(0.1111)), ndigits=2))
>> 0.12

# Note: this only affects the rounding of `Decimal`
round(0.1111, ndigits=2)
>> 0.11

Here are some examples:

round_up(0.022499999999999999, 2)
>> 0.03
round_up(0.1111111111111000, 2)
>> 0.12
round_up(0.1111111111111000, 3)
>> 0.112

round_up(3.4)
>> 4.0

# @jpm - boundaries do what we want
round_up(0.1, 2)
>> 0.1
round_up(1.1, 2)
>> 1.1

# Note: this still rounds toward `inf`, not "away from zero"
round_up(2.049, 2)
>> 2.05
round_up(-2.0449, 2)
>> -2.04

We can use it to round to the left of the decimal as well:

round_up(11, -1)
>> 20

We don't multiply by 10, thereby avoiding the overflow mentioned in this answer.

round_up(1.01e308, -307)
>> 1.1e+308

Original Answer (Not recommended):
This depends on the behavior you want when considering positive and negative numbers, but if you want something that always rounds to a larger value (e.g. 2.0449 -> 2.05, -2.0449 -> -2.04) then you can do:

round(x + 0.005, 2)

or a little fancier:

def round_up(x, place):
    return round(x + 5 * 10**(-1 * (place + 1)), place)

This also seems to work as follows:

round(144, -1)
# 140
round_up(144, -1)
# 150
round_up(1e308, -307)
# 1.1e308