A baseball card store can obtain Mel Schlabotnic rookie cards at a cost of $5 per card. The store has been offering the cards at $10 apiece and, at this price, has been selling 25 cards per month. The store is planning to lower the price to stimulate sales and estimates that for each 25-cent reduction in the price, 5 more cards will be sold each month. At what price should the cards be sold to maximize total monthly profit?