Some years corporations pay taxes and other years they get substantial refunds but the price of their product rarely fluctuates. Pepsi lost money at the end of the 1990's and was making money and paying taxes a few year later but the cost of their product did not change.
On to another point... don't you think that the fair tax will cripple the durable products industry? You buy a new car or sofa and pay 30% tax when I can buy a second hand one or refurbish my existing products? I could pay someone off the books to reupholster my sofa. I avoid the tax on his labor and since he did not pay tax to buy the new fabric then no tax revenue is collected. The black market and tax avoidance are large problems of the fair tax. That and it currently violates the Constitution.