Explanation: The hundred thousandths place is in the fifth place after the decimal. To avoid remembering this, you can simply note that the first place after the decimal is the tenths. You simply keep progressing as you would in whole numbers.
For example 10 becomes 100 when a zero is added. This zero is always added right beside the first zero and indicates the hundreds place.
Furthermore, the general rule for rounding is if the number after the preferred rounding place is 4 or less, the number remains the same. 5 or more means it goes up by one digit.