I have a problem with group discount being calculated incorrectly on checkout. The discount is being calculated on the value including VAT and then deducted from the value excluding VAT.

Example:-
Product price = 2750.00 ex. VAT
Group discount = 25%
VAT = 14% (South Africa)
Shipping is free

What I see is:-

Sub-Total: R2750.00
Store Pickup (Walk In): R0.00
Group Discount: -R783.75
V.A.T.: R288.75

Total: R2255.00

Discount should be 2750.00 *.25 = 687.50

What I expect to see is:-

Sub-Total: R2750.00
Store Pickup (Walk In): R0.00
Group Discount: -R687.50
V.A.T.: R288.75

Total: R2351.25

Is there an error or am I doing something wrong? I am using version 1.3.0