Mathematics for IGCSE & O level - Estimation (Section 2 - No. 35)
If the digit to the right of the desired decimal place is 5 or greater, what do you do?
Leave the digit as it is.
Round the digit down.
Round the digit up by 1.
Change the digit to zero.
Paliwanag
When the next digit is 5 or greater, round the digit up by one.