Part Dollar Subscription Charges

Whilst setting up 3 subscription levels using the Membership plugin, I noticed that the price drop down list gives the charge options in whole dollars.

I need to set up 3 subscription levels with the follwing monthly charges that offer a percentage reduction as the level goes up:

The site will offer product services with a basic product price of $0.50 per product per month

Bronze - Provides 5 Product Services @ $2.50 per month ($0.50 each)
Silver - Provides 10 Product Services @ $4.50 per month ($0.45 each = 10% off)
Gold - Provides 20 Product Services @ $8.00 per month ($0.40 each = 20% off)

As you can see, 2 of the subscription levels require the ability to charge in between full dollar amounts.
How to configure the plugin to allow me to charge these prices. Being restricted to whole dollars does not allow the flexibility required.

I hope you can provide a solution.

Regards

Colin (Locusuk)