I'm trying to write a formula using a combination of the MROUND and IF functions. I can't get it to work. Basically here's the scenario: I've got a formula that's already working to calculate into a cell (for example: B4). I plan on hiding that column (hypothetically B) of cells and put this MROUND formula into, say, H4.

Ultimately, I want H4 to take the results of the formula in B4 and round them the nearest multiple...

BUT there are conditions.... Different "multiples" depending on how large the number is:

Round to 3's - if the result is 1 to 18
Round to 6's - if the result is 19 to 36
Round to 12's - if the result is greater than 37

I also need to add an "IF" statement to the effect that if the result in B4 is "0" that H4 will reflect a hyphen only "-" rather than a zero.

Any help would be appreciated! Thank you