As explained by @Mike9241 you only pay tax on your winnings based on your tax bracket.
If you are in the 15% tax bracket, then you will pay 15% on your winnings; $600 x 15% = $90.
If you are in the 25% tax bracket, then you will pay 25% on your winnings; $600 x 25% = $150.
Keep in mind that you may also be subject to state income tax, unless you live in a state that does not have state income tax.
*A reminder that posts in a forum such as this do not constitute tax advice.
Also keep in mind the date of replies, as tax law changes.
