Great idea. Making a donation to the C&TS will reduce the amount of tax paid to the Feds and the state, because you can claim it as a deduction in your income.
However, if you make a $250 donation to them, your taxes will not be reduced by $250, but your taxable income will be reduced by $250, and the tax savings will by $250 times your tax rate
IF your tax rate for the feds is 8%, then your tax savings to the federal government would be $250 * 0.08 or $20.
I still support donating to the C&TS regardless of how much it actually may save you on your taxes.