42.052
place value and digits:
4 = tens
2 = ones
0 = tenths
5 = hundredths
2 = thousandths
5 is in the hundredths place. To find if you round up or down, look at the digit to the right (thousandths in this case). It is a 2, which is less than 5, so you round down.
42.052 rounded to the nearest hundredth is 42.05
hope this helps