I am encounter this problems when issue the purchase invoice.
My supplier will give me cash discount 3% for the cash payment.
For Example, if the product is $12.35, quantity is 12, total bill is $148.20, with the GST, the amount will become $157.09, then i will deduct 3% from $157.09. Final i need to pay $154.09
But when i use the format of purchase invoice and i put it 3% discount, the figure is different.