This should give you an idea what you can do. See if I got Formula 1 right:
Code:
Public Function Retains(InFee As Double, Market As Double, InFormula As Integer) As Double
Select Case (InFormula)
Case 1
Select Case Market
Case Is < 200000
Retains = Market * (0.007 / 4)
Case Is < 500000
Retains = ((Market - 200000) * (0.0069 / 4)) + 350
Case Is < 1000000
Retains = ((Market - 500000) * (0.0065 / 4)) + 867.5
Case Is < 2000000
Retains = ((Market - 1000000) * (0.0059 / 4)) + 1680
Case Is < 3000000
Retains = ((Market - 2000000) * (0.0058 / 4)) + 3155
Case Is < 5000000
Retains = ((Market - 3000000) * (0.005 / 4)) + 4605
Case Else
Retains = ((Market - 5000000) * (0.004 / 4)) + 7105
End Select