您可以使用四舍五入运算符最多为2小数

num = round(343.5544, 2)
print(num) // output is 343.55

可以使用python“%”的字符串格式化操作符。 “%。“2f”表示小数点后2位。

def typeHere():
    try:
        Fahrenheit = int(raw_input("Hi! Enter Fahrenheit value, and get it in Celsius!\n"))
    except ValueError:
        print "\nYour insertion was not a digit!"
        print "We've put your Fahrenheit value to 50!"
        Fahrenheit = 50
    return Fahrenheit

def formeln(Fahrenheit):
    Celsius = (Fahrenheit - 32.0) * 5.0/9.0
    return Celsius

def printC(answer):
    print "\nYour Celsius value is %.2f C.\n" % answer

def main():
    printC(formeln(typeHere()))

main()

http://docs.python.org/2/library/stdtypes.html#string-formatting

round(12.3956 - 0.005, 2)  # minus 0.005, then round.

答案来自:https://stackoverflow.com/a/29651462/8025086

不知道为什么，但'{:0.2f}'.format(0.5357706)给我'0.54'。 唯一适合我的解决方案(python 3.6)如下:

def ceil_floor(x):
    import math
    return math.ceil(x) if x < 0 else math.floor(x)

def round_n_digits(x, n):
    import math
    return ceil_floor(x * math.pow(10, n)) / math.pow(10, n)

round_n_digits(-0.5357706, 2) -> -0.53 
round_n_digits(0.5357706, 2) -> 0.53

如果你只想输出四舍五入的结果，你可以使用Python 3.6以来引入的f字符串。它的语法与str.format()的格式字符串语法相同，不同之处在于在字面值字符串前面加了一个f，并且将变量直接放在字符串中，放在花括号内。

.2f表示四舍五入到小数点后两位:

number = 3.1415926
print(f"The number rounded to two decimal places is {number:.2f}")

输出:

The number rounded to two decimal places is 3.14

from decimal import Decimal, ROUND_HALF_UP

# Here are all your options for rounding:
# This one offers the most out of the box control
# ROUND_05UP       ROUND_DOWN       ROUND_HALF_DOWN  ROUND_HALF_UP
# ROUND_CEILING    ROUND_FLOOR      ROUND_HALF_EVEN  ROUND_UP

our_value = Decimal(16.0/7)
output = Decimal(our_value.quantize(Decimal('.01'), 
rounding=ROUND_HALF_UP))
print output