Our pricing structure is set up that one to three items is $4 each. If the customer buys four items the cost is then four for $15. If they buy 7 items the cost would be $27 ($15 for the first four and $12 for the next three).
How do I set this up so the pricing works based on the purchase of four items for a reduced price and then for items five through seven for full price in addition to the discounted price?
TIA for your help!