You could do something as simple as, place three buttons on your worksheet and add three separate codes to your VBA. Assign the buttons to the codes below.
Change the Range to wherever you want the percentage.
Code:
Sub Push_Button_1()
Range("A1").Value = "1.1"
End Sub
Code:
Sub Push_Button_2()
Range("A1").Value = "1.2"
End Sub
Code:
Sub Push_Button_3()
Range("A1").Value = "1.25"
End Sub