Applying Shipping Discount on Invoice

[atxpoint1]

I'd like to subtract an amount as a shipping discount on items that were listed as Free Shipping. When I enter the negative amount in the Discount box ("Seller discounts (-) or charges (+)"), this message appears: "Invalid discount amount. You may only provide a discount on shipping, insurance, and/or tax." Okay, well I can't enter a negative number in the shipping box, so...

[femmefan1946]

You can't have negative shipping. The lowest price is Free. Which is what you offer.

You can't change the price of the item once the purchase is made.

You can send the buyer a payment through Paypal's Send Money. Remember to tell the buyer why you are doing this.

But if he thought he was getting a good deal anyway, is there a reason to give a further discount? Remember if you are using Paypal for your shipping label that the amount of postage does not show.

To complicate matters, the value of the postage stamps on a mailout is not the amount the shipper pays at the PO counter. The face value of the stamps does not include sales tax and fuel fees. The PP label does not reflect the 5%to 18% discount the user gets off PO counter prices.