Which files calculate the total price of each product?

Hello, I have now looked for hours, but OC's code is still a big jungle to me.

I want to find the files where it calculates the total price of each product.
I tried following the price_prefix from the options, but that was a dead end to my surprise.

Did you find it?
If so please tell me what it is.
Thank you

totals where? In the cart? the cart class pulls the data from the database and adds it together.
All the main classes are in system/library

There is a getSubTotal() function in the system/library/cart.php file that gets the totals of all products + options