DBTax and DBtaxPerBill inconsistant sign (+/-) resulting in incorrect sum

[sjshaffer]

Discount per item (DBtax) and aggregate discount (DBTaxPer Bill) have opposite signs in the discount column of the invoice and the discount sum is incorrect however the total is correct.
These are the rules that were applied to the attached order:
Wine Club 6   Everyday Discount for 6 bottle club members   0   DBTax   -%   15.0000   United States dollar         Wineclub_6   1970-01-01   -Never-
5% off 1/2 case & 10% off case or more   Save 5% on 6 to 11 bottles & 10% on a case (12 botlles) or more   0   DBTaxBill   -%   0.0000   United States dollar   Wine         1970-01-01   -Never-   
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