Answer:
6.000
Explanation:
You have to round the last decimal place (3rd) based on the following number (5.9995). Since it is greater or equal to 5, you'll have to round it up. However, if you round up 9, it becomes 0, and ads one to the previous digit, and propagates back all the way.
5.9995 by rounding to 3 digits, you'll have to check the fourth digit. 5 rounds up last 9
5.99[9+1] this becomes 0 and adds one to previous
5.9[9+1]0 also becomes 0 and adds one to previous
5.[9+1]00 same again
[5+1].000
6.000