Hi Ron,
I am having the same sort of problem with PSIgate only with a percentage discount:
Sub Total: $79.96
Discount: $19.99
Postage: $9.51
Handling: $3.00
Tax: $5.55
Total: 78.03
Only the Psigate invoices the custome $98.02 - it does not recognize the Discount
I am using the PSIgate XML sent to me by Psigate - its by Jason LeBaron