Rounding decimals works almost exactly the same as rounding numbers. You will usually need to round a decimal either to a whole number or to one or two decimal places.
To round a decimal to a whole number, focus on the ones digit and the tenths digit. Round the decimal either up or down to the nearest whole number, dropping the decimal point:
When the tenths digit is 5 (or greater), round the decimal up:
If the decimal has other decimal digits, just drop them:
Occasionally, a small change to the ones digits affects the other digits. (This may remind you of when the odometer in your car rolls a bunch of 9s over to 0s):
The same basic idea applies to rounding a decimal to any number of places. For example, to round a decimal to one decimal place, focus on the first and second decimal places (that is, the tenths and hundredths places):
To round a decimal to two decimal places, focus on the second and third decimal places (that is, the hundredths and thousandths places):