Rounding of a number to nearest tenth or hundredth means we approximate it and for this we do not need a number beyod tenth or hundredth,
As we have in decimal number system, a number from 0 to 9 at a place,
if we have a number from 0 to 4, we remove the numbers beyond those desired completely - for example if a number is 3.14159 and we need to round it to nearest hundredth, as we have 1 next to number in hundredth place, we just ignore it and write 3.14.
if we have a number from 5 to 9, we remove the numbers completely, but add 1 to the last desired digit- for example in the given case $21.38 and we need to round it to nearest tenth, as we have 8 next to number in tenth place, we ignore it but add 1 to 3, which is the last digit and rounding $21.38 to tenth place, it becomes $21.40.
