Quantity Discount : 28.75% to 36.25% off 5+ @ 28.75% : 543.43 + 97.82 (18%) = 641.25 10+ @ 32.50% : 514.83 + 92.67 (18%) = 607.50 15+ @ 36.25% : 486.23 + 87.52 (18%) = 573.75