Since you are rounding to the nearest whole (the ones-place-digit), look at the tenths digit (the digit right after the decimal point)
In this case it is a 5. If the number is 5 or greater (like the number given) you will round up
37.52 will become 38
If it is 4 or lower, round down. So for example, if it is 37.49, then your answer will be 37 (if you are still trying to find a nearest whole)
So 38 is your answer
hope this helps