Would you like to have Paypal add $5.52 to a donation to your favorite charity?
"Become a giver
In celebration of Giving Tuesday, beginning today through the end of December, we’ll make your gift go further.
We’ll add $5.52 (the cost of 12 stamps) to your favorite cause
100% of your donation will reach the charity you select"
It appears to be limited to the charities on their list, but the list is pretty extensive. I didn't find the specific charity I was looking for (I emailed them and asked them to register) but I found several local charities in the same vein I could donate to.