Do you have to pay for an item which you accidentally broke in a store?

Unfortunately a store can set its own policies regarding the condition of its merchandise. Whereas it doesn't appear that you had any bad intentions or handled it improperly you will always run into places that are stubborn in this respect. If you explained your story and there was still no success the only thing you could've done is maybe talk to a manager about it as they sometimes are more willing to make the "tougher" calls on these sorta things. Luckily it wasn't something overly expensive. Hope this helps!