Hello.
I need to increment quantity in product page from 5 to 5, for example when user click + in quantity textbox will apear 10 , 15, 20 , 25 and same when click - 25, 20,15 , 10, 5, etc
What file is corecponding to product page?
I looked in product page tpl but i can't make changes there, i need to make changes in a javascript file corespondind to product page