Conditional Format Based on Field Value - Number/Percentage

I am attempting to change my MTD, QTD, YTD values to percentages where appropriate.

I have a dynamic measure that gives me both whole numbers and percentages.  I am trying to figure out how to write a measure that I can apply to the custom formatting function option.

I've gotten as far as:

Dynamic_Format = 
   VAR CurrentValue = SELECTEDMEASURE()
   VAR FormatAsPercent = FORMAT(CurrentValue, "0.00%")
   VAR FormatAsWholeNumber = FORMAT(CurrentValue, "0")
RETURN

???

but I'm not sure where to go from here.  Additionally, my dynamic measure has a slicer attached to it based on this table:

Where I added a DataType column hoping to do something like, IF 1 then FORMAT(as whole number), IF 2 then FORMAT(as decimal), IF 3 then FORMAT(as percentage).... something to that effect.