If you need to round a number to the nearest multiple of 5, you can use the MROUND function and supply 5 for number of digits.
How this formula works
In the example, cell C6 contains this formula:
The value in B6 is 13 and the result is 15 since 15 is the nearest multiple of 5 to 13.
As you’d expect, you can use MROUND to round to other multiples as well:
And so on.
If you need to force rounding up or down to a nearest multiple, see links to the CEILING and FLOOR functions on this page.