@dougmcbride79 This cannot be achieved both in Acumatica and BigCommerce. None of the systems accept to have more one Customer Price Class/Customer Group per Customer. 

I would suggest you to create Customer Price Class based on Item Class. Meaning have one Customer Price Class with respective to Item Class A and another one with respective to Item Class B. By this you can create discounts easily per Customer Price Class/Customer Group/Item Class.

Could you please further explain our suggested solution.  I am not understanding it.  

Create one Customer Price Class in Acumatica per Item Class. 

Example: If you have two Items classes A and B then create two Customer Price Classed Retail and Wholesale. Assign all the Customers from Item Class A to Retail and Customers from Item Class B to Wholesale. See below table. The number of Customer Price Classes should be always equal to number of Item Classes. 

I greatly appreciate your example.  Your example solves my issue on the Acumatica side.  My second concern in on the Big Commerce side.  In Big Commerce I believe I can only put the customer in one Customer Price Class / Customer Group.  I need the customer to be in two Customer Price Classes in Big Commerce like I have the customer in Acumatica.  How can I get both Customer Prices Classes to apply to a customer in Big Commerce?

@dougmcbride79 Please recheck my previous responses. Even in Acumatica, you cannot assign a same customer to more than one Customer Price Class or Item Class. Likewise, this cannot be done at BigCommerce as well. 

My suggestion is to have the Customer Price Class/Customer Group per Item Class. By doing this, you can assign discounts per Item Class and that's it. You still wont be able to assign a same customer to more than one Customer Price Class or Customer Group or Item Class. 

Thank you for the clarification.  I appreciate your guidance.