unintentionally different price for end customer for other country due to TAX

I am running the ELITE Version and a google shopping feed for Germany and its working fine since months. The price of a product is 139€ (incl. German TAX of 19%). Now I created a additional Google Shopping feed for France incl. absolutely the same information but he shows me <g:sale_price>EUR 140,17</g:sale_price> in the feed instead of 139€. These prices do not look good! In France the TAX is 20% instead of 19% compared to Germany. BUT in my online Shop the final price for the customers is for both countrys (FR/DE) 139€, only the TAX is different. It is a product with different variations and different prices.
What do i have to set so that the end customer prices are exactly the same as in germany?