on the calculations tab, create a new calculation as:
discountAmount
(abs([Quantity] >= 5 && [Quantity] < 10)?[Price] * 0.05:0) + (abs([Quantity] >= 5 && [Quantity] < 10)?[Price] * 0.1:0)
then on the discount tab, create a discount as:
Trigger:
Subtotal of column discount amount > 0
calculation:
Subtotal of column discountAmount plus 0