How do I round a number up to the next 500 or 1,000???

I need a formula that will round a number up to the next 500 or 1,000. For example, if I have the number 31,150, I need the formula to round the number to 31,500; or if the number was 31,600, I need the formula to round the number to 32,000. I tried using the round function but cannot make it work as I need it to. Is there any way to do this?

Thanks in advance,
Kevin Skinner