Add a "Margin" Surcharge to a Discounted Price

We have a requirement to add a "Margin" surcharge to a discounted price on a quote. The scenario is as follows:

The customer gets a discount off of the list price of 20%.  There is then a 12% margin applied to the discounted price.

EXAMPLE:

List Price = $1200

Customer Discount Price = List Price - (List Price * Customer Discount) or 1200 - (1200 * .20) = 960

Margin Price = Customer Discount Price / (1 - Margin Percentage) or 960 / (1 - .12) = 1090.91

We are using buckets to ensure that the pricing happens in the correct order.  The first discount would be Bucket 1 and the second Bucket 2.

Where we are having the issue is passing the discounted price from the Bucket 1 discount into the formula for the bucket 2 surcharge.  Any ideas on how to achieve this would be greatly appreciated.