Americans of all income levels give back, but it’s the richest who reap almost all of the benefits of the charitable tax deduction. | J. David Ake/Getty Images Ah, Tax Day.  If you’ve been staring at your tax bill and wondering how to keep more of your money, money, money to yourself next year, you might consider taking a page out of the billionaire’s playbook . You could be like Steve Ballmer and write off the costs of buying a sports team , or make like Mark Zuckerberg and dial down your salary to just $1 per year .  Or, if those things seem daunting, you might just donate to charity instead. Every year, the US Treasury loses upward of $65 billion in revenue — enough money to pay for a national universal pre-K program by one count — to charitable deductions. But while Americans of all income levels give back , it’s the richest Americans who have reaped almost all of the benefits on their tax bill.…