Quantity Discount : 28.75% to 36.25% off 5+ @ 28.75% : 452.86 + 81.51 (18%) = 534.37 10+ @ 32.50% : 429.02 + 77.22 (18%) = 506.24 15+ @ 36.25% : 405.19 + 72.93 (18%) = 478.12