Originally Said By: Ray Borduin
You could add a new "Apply coupon" button that refreshes the page and shows the updated discount so they can see the new price before pressing the checkout button. 
I'm almost done, but I can't make the cart value set to 0 with discount.
Example:
The regular item price is 0.01€.
The coupon should allow to set the item price to 0,00€ (free).
But the discount work only if the resulting price is not 0.
Example:
The regular item price is 0.02€.
The discount is subtotal (0.02) minus 0.01.
This way it works and I get the cart to be 0.01€.
Again, if I set the price to 0.02€ and the discount to subtotal minus 0.02, it doesn't work and I get the price 0.02€.
But how can I set the price to be 0 with a coupon code?
Is there something else to look at in the cart definition?
Or perhaps is Paypal that does not allow 0 money transactions?
How can I solve this problem, in this case?
TIA
tony
