If you take the square root of 108 you’ll get 10.39 so the nearest tenth would be 10.4
If it helps the number stays the same if it’s under 5 and if it’s over five it goes up a number. For example if you have 34.62 it would just round to 34.6 but if you have 34.67 it would round to 34.7. It works with all decimal places.
Hope this helps