Teethless mama wrote:
=ROUNDUP(A1,-2)

That rounds up to the nearest __100__, not nearest 500 except by
coincidence. It works with the OP's example (525446). But
roundup(525321,-2) is 525300, not 525500.

That might, indeed, what the OP meant. But....

"Heather" wrote apparently:
Call me crazy, but I have read every rounding question and answer and I
cannot get Excel to round up to the nearest 500.
IE: 525446 needs to be 525500

Are you sure that is what you really want? Be sure to test any
solution offered with a variety of numbers. For example:

=500*roundup(525446/500, 0)

yields 525500, as you wish. But:

=500*roundup(525501/500, 0)

yields 526000. That is what "roundup to the nearest 500" means.