Everyone who buys an item for $100 will see the exact same tax on their receipt. The receipts will not vary according to each persons different effective rate. How would the retailer know my effective rate?
You are clearly talking about a $100 purchase including the FairTax showing on the receipt. I have answered your question - the amount of the real cost to you would be $85.65 due to your effective tax rate.
The fact that you do not like my answer does not matter a bit - it's still the case and shows how the FairTax actually operates - like it or not.
I'm just happy to know that my current cost of $100 would rise to $130 under the FairTax. Thanks.