Dynamic Custom Rates let one coupon give a bigger discount as the cart grows. Click the + icon next to Dynamic Custom Rates to add a row with:

• New Coupon Rate — the value (or percentage, depending on the coupon Type) for this tier.
• Minimum Cart Value Required to Apply Coupon — the subtotal at which this tier kicks in.

Use the red Delete button to remove a row. Rows left with both fields at 0 are ignored on save.

At checkout Sprwt sorts the base rule and all tiers by minimum, then applies the highest tier whose minimum the subtotal reaches. If the subtotal reaches none of them, the coupon is refused with "This coupon is only valid for checkouts min. $X" (X being the lowest minimum). Tiers with a minimum lower than the coupon's base Minimum Cart Value Required are skipped. The tier used is recorded on the order.