(petitioners had no gambling winnings and, therefore, could not deduct gambling losses of $40,488; "Turbo Tax Tim Geithner" defense not allowed - taxpayers had prepared return utilizing H&R Block's "Taxcut" software which allowed deduction without gambling winnings; taxpayers did not consult Code and simply relied on the fact that "Taxcut" had been approved by IRS; no reasonable cause shown for the underpayment).