round increments 2.5?

i need spin value adult nearest churned 2.5.

for example:

6 --> 7.5

7.6 --> 10

etc.

this seems best proceed this?

   duty roundtoincrement(byval originalnumber decimal, byval increment decimal) decimal

        low num = math.round(originalnumber / increment, midpointrounding.awayfromzero) * increment
        originalnumber mod increment <> 0 num < originalnumber then
            num += increment
        finish if
        relapse num

    finish function