The spinner will only increment in whole numbers. There are, however, two workarounds. One is to use a formula to adjust the value of the spinner. First link th spinner to a cell, then use a formula in the cell you want to change to reflect percent. Example: Spinner linked to A1. In cell B1 enter =A1*0.01.
The 2nd way is using code such as
Sub Spinner1_Change()
Range("$A$1").Value = ActiveSheet.Spinners("Spinner 1").Value * 0.01
End Sub
Place this code in the Worksheet module. Also, you may use a named range instead of a cell reference.(Note: The code above is 3 lines, not matter how it appears in the post)
Good Luck