Add option to cap discounts after a set quantity

I would like the ability to cap the discount after a certain number of units. For example:

• 2 units → $10 off

• 3 units → $20 off

• 4 units → $30 off

• 5 units → $40 off (cap)

If a customer adds more than 5 units, the additional units should be at the regular price with no further discount applied. This would help prevent over-discounting and allow more control over promotional campaigns for bulk purchases.