I've been looking through the code and have come up with the following concept.  Please review and let me know if this seems reasonable:

Modify code on CatlooKnetStore.Library/CodeBehind/ShoppingCart.apx.vb as follows:

1. Modify CheckoutBtn_Click Event to pass an additional parameter for CartGoodsPrice to GetCouponAmount function as follows:

Private Sub CheckoutBtn_Click(ByVal sender As System.Object, ByVal e As System.Web.UI.ImageClickEventArgs) Handles CheckoutBtn.Click

If Page.IsValid = True Then

Dim cart As ShoppingCartDB = New ShoppingCartDB

' Calculate shopping cart ID

Dim cartId As String = cart.GetShoppingCartId()

If tbCoupon.Text <> "" AndAlso CType(Settings("CATCart_CouponCodes"), String) <> "" AndAlso Not IsNothing(Settings("CATCart_CouponProductID")) AndAlso CType(Settings("CATCart_CouponProductID"), String) <> "" Then

REM - BEGIN modified for percentage coupon discounts - STW - 5.9.07

'original code

'Dim CouponAmount As Double = GetCouponAmount(tbCoupon.Text) * -1

'new code

Dim objCartPrice As New CartPriceInfo

Dim objCartPrices As New CartPriceController

objCartPrice = objCartPrices.GetCartPrice(UserId, GetShipToID, PortalId)

Dim CouponAmount As Double = GetCouponAmount(tbCoupon.Text, objCartPrice.CartGoodsPrice) * -1

REM - END modified for percentage coupon discounts - STW - 5.9.07

1. Modify GetCouponAmount function to handle the existance of a percentage symbol and calc the discount based on the percentage x order total

Public Function GetCouponAmount(ByVal CouponCode As String, Optional ByVal OrderSubTotal As Double = 0.0) As Double

Dim arrCoupons() As String
Dim CouponAmount As Double = 0
Dim CouponCodes As String = CType(Settings("CATCart_CouponCodes"), String)

CouponCodes = CouponCodes.Replace(ControlChars.CrLf, ";")

Dim delimiter As String = "=;"

arrCoupons = CouponCodes.Split(delimiter.ToCharArray)

If Array.IndexOf(arrCoupons, CouponCode) <> -1 Then

Dim Amount As String = Convert.ToString(arrCoupons.GetValue(Array.IndexOf(arrCoupons, CouponCode) + 1))

If IsNumeric(Amount) Then

CouponAmount = Convert.ToDouble(Amount)

If RemoveUsedCoupons Then

Dim RemoveString As String = CouponCode & "=" & Amount

Dim newCouponCodes As String = CType(Settings("CATCart_CouponCodes"), String)

Dim StartIndex As Integer = newCouponCodes.IndexOf(RemoveString)

Dim CharsCount As Integer = RemoveString.Length

If StartIndex + CharsCount + 2 > newCouponCodes.Length Then

newCouponCodes = newCouponCodes.Remove(StartIndex, CharsCount)

Else

newCouponCodes = newCouponCodes.Remove(StartIndex, CharsCount + 2) 'incl. crlf

End If

Dim objModuleController As New ModuleController

objModuleController.UpdateModuleSetting(ModuleId, "CATCart_CouponCodes", newCouponCodes)

End If

REM - begin percentage discount coupons modification - STW - 5.9.07

Else 'coupon contains a non numeric character

If InStr(Amount, "%", CompareMethod.Binary) = 1 Then

CouponAmount = (Convert.ToDouble(Amount) / 100) * OrderSubTotal

End If

REM - end percentage discount coupons modification - STW - 5.9.07

End If

End If

Return CouponAmount

End Function

Does this look like I'm on the right path?