Commerce Rules OR Condition
This thread helped me understand the logic.

https://www.drupal.org/node/1784196

Basically what tobiasb said:


  OR (All conditions below this or between the lines are OR-Conditions)
  - condition1 (OR)
  - AND  (All conditions below this or between the lines are AND-Conditions, default condition)
  -- condition2 (AND)
  -- condition3
  
  This means:
  
  condition1 OR (condition2 AND condition3)