Even if you got audited nothing about goodwill purchases has anything to do with taxes.
I think if you make donations you can use them as a write off but as far as purchases that should only be for personal use.
That is like keeping all your gamestop receipts or receipts from eating out, nothing about that has to do with your taxes.
If you itemize your deductions, one of which can be sales tax
You can elect to deduct state
and local general sales taxes
instead of state and local income taxes. You cannot deduct both.