For tax purposes, your selling price is the net after all credits. The IRS doesn't care if you sell for $100,000, or for $115,000 with a "seller credit" of $15,000. The selling price for tax purposes is $100,000 either way.
The bank might care, since using an inflated selling price might allow the buyer to get a bigger mortgage than they should, but that's between them and the bank.
