2.5 Incremental formula needed

Thanks in advance for your help!!!


I have this formula:

C10=C1*H6/100

Actual example is
=54*65/100

And I get 35.1

I want to add this function to the statement

The answer has to be within an increment of 2.5 and rounded up/down to whatever was closer.

So 35.1 would be round down to 35 and show 35 and not 35.1

Increments are like this, so anything in between these numbers would have to show the answer as one of these:
30, 32.5, 35, 37.5, 40

So if I got 35.5, if would be 35 that would show
36 would be 35
36.5 would be 37.5

30 range is just an example, so I would like a formula that goes from 0-100.

thank you!