Subscriptions Percentage

[Nabix]

I'm using commerce and noticed that when you create a product for a subscription, users can be set to have discounts. But it is only in currency (USD). Is there a setting for percentage instead of just a set amount? Is the discount only for the product itself. What I need to do is setup a subscription when users have paid the fee that are allowed a percentage discount for every product in the downloads for the duration of the subscription.