Quantity Discount : 28.75% to 36.25% off 5+ @ 28.75% : 422.67 + 76.08 (18%) = 498.75 10+ @ 32.50% : 400.43 + 72.08 (18%) = 472.51 15+ @ 36.25% : 378.18 + 68.07 (18%) = 446.25