Two Columns and Multiplication in a Matrix?

Hello, 

I need help with the following, which I have been battling with for some time. 

I basically have data that looks like this: 

The rows in yellow are the most recent transactions per product and customer ID that I need to display in a matrix. So far, I have been able to do this and it is giving me what I need: 

The problem is that I would like to add next to each product the costs displayed in the Excel sheet above and then multiply each value * costs% in a new column. These costs change every reporting period so that there can be several lines for each product and customer. But when I try to pull up the costs column into a visual, Power BI returns all the costs that are in the data model and the total is wrong. So for example, for customer 22 I am getting the following: 

Instead of just this: 

Next I would like to display 280.488 * 1,73% = 4852,44. 

Is there any way I can do this? I tried to create a summary table with two columns - value and costs - but it is not working (otherwise I wouldn't be here).

Thank you for your help.