In traditional accounting methodology Tom taxes aren't figured in until you actually make a profit, what you do is determine the rate of return you want and work out the structure it takes to get there. A market will pay a certain amount for a product and they won't pay just any price. Tax doesn't drive the business Tom, it is entirely wrong thinking to think it does
Now if you are operating with a GST that is a horse of a different colour since that is outside the profit structure