Comment by rtkwe

The issue with "common sense" is there's no way to run anything based on it because you'll get 100 different ideas of what that means in any situation. 90% of customers would be fine with the rounding to the nearest 5 cent plan but there's a streak of stubborn people who'd refuse to accept it and waste some legal time trying to get proven 'right' so the stores want legal clarity so they don't have to deal with that.