Q. Is it correct for the Gabaim in charge of a Pushka or Tzedaka collection box place a sign on it that they don't accept pennies or Tzedaka Vouchers?
A. Although one may argue that the Gabai or Gabaim in charge of the collection boxes may be affecting negatively the total amount of the Tzedaka that could have been collected by not accepting the vouchers and that could be far more significant than not accepting pennies.
Pennies have been phased out of Canadian currency for cash transactions on February 2013, however they can still actually be deposited in a bank when rolled in rolls of 50 coins.
Horav Shlomo Miller's Shlit'a opinion is that since the Gabai or Gabaim are usually donating their time, they are entitled to qualify their given time and effort to conditions that are easier and more productive for the time donated, and one should try to comply to their conditions.
However, the Rov maintains that the vouchers or pennies deposited in the pushka are anyway considered Tzedaka.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit'a