The first decimal place is the tenths.
The second decimal place is the hundredths.
The third decimal place is the thousandths.
When rounding to the hundredths, you want to look at the thousandths place.
If the number is greater than or equal to 5, the hundredths decimal will increase by one.
If the number is less than 5, the hundredths place will stay the same.
In this case, the 6 is greater than 5, so the hundredths place will increase by one.
This should be your answer: 3.88