Buy gift cards for your favorite merchants at face value - a $100 card costs $100. The merchant then makes a donation to the WR/SS JCC equal to a percentage of the value of the card.
Each time you shop, you give the checkout clerk your card and the amount you spend is deducted. The remaining balance appears on your cash register receipt.
If the store has an incentive program, e.g. Save-On-More points, you still get those.