If you want to round 98.155 to the nearest tenth, it is 98.2. The 1 is in the tenths place. If the number to the right of it is 5 or more, round up. If the number to the right of it is 4 or less, round down. In this case, you round the digit in the tenths place up because the digit in the <em>hundredths</em> place is 5+.
The tenth is the first decimal place. When rounding you check if the number before is greater than 5, if it is you add 1 to the previous number, else you leave it as it is.
