A national sales tax would be fair to ALL Americans. In addition, a sales tax would apply to all people purchasing goods in America. If the income was from ill-gotten gains, under the table money or earned by illegal immigrants, the taxes would still be collected.
The size of the I.R.S. could be greatly reduced, saving billions of tax dollars. (and other issues)
Food items and prescription drugs should be tax exempt in order to not burden the poor and elderly. This would apply to all Americans, and therefore would remain fair to all.