Just how….

You can use quantity based discount rule for achieving this.
Steps:
Create a Product List with the selected products / category
Now create a Pricing Rule, set Discount Type as ‘Quantity based discounts’, make sure you have selected the created list.
Now under ‘Quantity Based Discount’ section select Type ‘Discount on individual product quantity’
Set the desired combinations
For ex:
Min Quantity: 5 – Max Quantity: 10 – Discount type: Fixed – Value(Discount value): 2
Min Quantity: 11 – Max Quantity: 15 – Discount type: Fixed – Value(Discount value): 5
Min Quantity: 16 – Max Quantity: – Discount type: Fixed – Value(Discount value): 7

I’m marking this as resolved. Please feel free to open a new thread if you have any further questions.