Hey Bob, basic math time. 2.9% + .35 of 1 dollar is not "double the amount". Let's just round it off, 3% of a dollar is 3 cents, meaning that a $1 donation will cost the donor $1.38. WOW! 38 cents more!
Let's crank it up to the $5 donation that gets you a mention or a thank you most of the time. 3% of that 5 dollars is 15 cents, so it's a total cost of $5.50. Now let's do 10 dollars, total cost is 10.65. At what point does the service charge equal a whole, extra dollar? 22 dollars, at which point the service charge is a bank-breaking $1.01.
WOOOOOOOOOOOOOOOOOOOOOW. So much money! Let me clean out my fucking couch cushions, I'll get the change for your goddamn service charge. It's cheaper then paying for my fucking sales tax of 8%!
Basically, anyone whining about how this service charge is "so much money" and it's "unfair to the patrons!" is a stupid fucking cunt.