how to round 9995.2 to the nearest ten?

             9995.2

The red 9 is in the ten's place.

Look at the number just to the right of this 9.
It is 5.  Since it is at least 5, you round the
red 9 up to 10.  But that carries to the 9s before
it and you have a 1 in front and a 0 in the ten's 
place (shown in red):

            10005.2

But don't stop there.  Replace the 5 by a 0 and
drop the decimal and the 2 on the end. You end
up with

            10000

Edwin