Override contrib module's theme I've been turning the internet upside down trying to find out how to simply override a contrib module's theme() file. Although I have find many ways that should work, no result pops up and I can't really troubleshoot why.

To be more specific, I want to override the output of the file (/sites/all/modules/contrib/commerce/modules/cart/theme/commerce-cart-block.tpl.php) through theme('commerce_cart_block').

Now, I've tried many things. I have tried something called suggestions trying trying to make a file named block--commerce--commerce_cart_block.tpl.php in my theme directory plus several other varies of names. I've also tried setting new path through custom_checkout_theme_registry_alter's passed array. But now changes are visible, with or without clearing the cache each attempt.

I'm clearly missing something since this should in my eyes be both easy to do and needed to be editable.

So the question in short; How can I with as good practice as possible override the theme file of a contrib module and use it's passed variables?
Copy commerce-cart-block.tpl.php file to your theme and edit that copy. Remember to clear your cache before you reload the page. That's all. Don't rename. Don't play with suggestions.