Why rounding 999 into the nearest tens?

Answer 1

You can round up 999 to the nearest tens (that is 1000). This is only applicable when you are doing a calculation involving very huge value, where using 1000 or 999 will have negligible effect on the final answer.

Answer 2

It doesn't matter with tens, hundreds or thousands you still get 1000 as the rounded answer.

Answer 3

There is no need to round it: leave it as 999.