Please stop "edit"
To answer to everyone asking the question:
We are two individual owners, Au revoir et merci website is the junction of the two small entities, and in France there is a special type of corporation that is exempted from paying VAT when selling.
But while you can go higher than suggested retail price, you can't go under... then you are free to refund VAT or not.
So to resume this point, In our situation, the VAT deduction that we apply on non-sale item, is a pure gift made to the customer since on each sale we don't pay it, and we must respect the suggested retail price, we do it only to to be more competitive, and actually I think that we are one of the most competitive store across the board.
There are also several additionnal reasons, just contact me if you have some additionnal questions.
Au revoir et merci.