Source: 📖 Python Cookbook ch3.1 p83

Rounding to tens, hundreds and thousands

The built in round() function can be supplied with two arguments—the number being rounded and the number of digits to round to. If supplied with a negative number for the second argument, the function will round the the respective number of spaces to the left of the decimal point, allowing you to round to tens, hundreds, thousands, and so on.

num = 123789
round(num, -1)	# 123790
round(num, -2)	# 123800
round(num, -3)	# 124000