Update the tiered discounts promotion to take into account the newly discounted price when calculating the cart value relative to the next tiered discount. For example, if a 10% discount applies at $20, and a 15% discount applies at $30: Buying 4 $5 items will achieve the first discount, but buying 3 of the newly discounted $5 items should achieve the second discount, not 2 (since the discounted price is $4.50 not $5.00)