If you issue a receipt, it must follow IRS regulations outlined in Publication 1771. That requires a statement reflecting the full amount paid, a description and value for the benefit, and a statement indicating the charitable amount is the difference between the two.
However, the IRS does not require a receipt for QPQ donations if the payment is less than $75. So, for these low dollar amounts, you can advertise or promote that $X will be considered deductible - but don't issue a receipt.
On the other hand, as only 1 in 10 taxpayers itemize these days, I'd consider not even bothering with any language regarding deductibility and promoting the event as a "proceeds to benefit" affair.
John
John H. Taylor
Principal
John H. Taylor Consulting, LLC
2604 Sevier St.
Durham, NC 27705
919.816.5903 (cell/text)
Serving the Advancement Community Since 1987