Exclude a free product from total calculation In Drupal Commerce, how can I exclude a product from partial total calculation? The product is inserted as free product via a Commerce Discount rule, but in total calculation it appears and then is subtracted. 
I would exclude this insertion/delete operation.
Create a rule with the event Calculating the sell price of a product.

There, you can check for the SKU of the product and set its price to zero (using the Set data value action).

You can also use the Subtract an amount from the unit price action to assign the value to a price component so that it appears in the totals (this will require extra configuration)