When using a fixed amount discount, I wanted to keep the shipping charge.

Currently, if a discount coupon exceeds the order total amount, the order total will be 0.

Example:
$50 Subtotal
$10 Shipping
-$100 Coupon
--------------
$0 Total

Now, you can choose in the Admin section to retain the shipping charge so that the total will not be 0. Discount will only apply to the subtotal, not the order total.

Example:
$50 Subtotal
$10 Shipping
-$100 Coupon
--------------
$10 Total

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