How to round BPM to 5 (92 to 90 or 93 to 95)

Hi, I would like to round BPM to 5 on my songs.

If I have 92 I want to round to 90 and if I have 93 round to 95.

How could I do it? Thanks

See there ...
Rundung auf 20er Schritte im Tag BMP
Set ... BPM_ROUNDBY=5

... or ...

BPM <== $mul(5,$div($add(5,$mul(2,%BPM%)),10))

DD.20150821.1352.CEST

Great!!! thank you