Subscription Plans: Quantity Discount

[sashasklar]

I'm working on an integration  for a SAASS that discounts cost per seat based on the number of seats in the subscription.

for example

1-5 seats is $10/seat

6-10 seats is $8/seat

10+ is $5 a seat

I've read through the docs on plans & subscriptions and it's not obvious how I'd go about implementing this. Any help?