Yeah, I agree with letsgoplayd. Your answer doesn't make any sense because 8164 is not a decimal. But we can look at another example:
8164.45678
In this case, the number rounded to the 4th decimal point (ten thousandths) would be
8164.45680
Because the digit after the 7 is 8, we should round the "78" part to "80".
These two rules will help:
5 or more, raise the score (add 1 to the digit, and let the digit directly behind it become 0.)
4 or less, let it rest (keep the digit, and let the digit directly behind it turn to a 0.)
Hope this helps! :)