There are several systems, but let's take a look at Outpatient procedure pricing...
A good outpatient pricing guide is here: https://www.cms.gov/Outreach-and-Education/Medicare-Learning...
And coupled with the OPPS dataset here: https://www.cms.gov/Medicare/Medicare-Fee-for-Service-Paymen... as well as a couple others, along with a quick read of the federal register, you can kinda figure it out on your own (/s).
Every bill you get must also have the codes and modifiers on it by law. Its interesting to download the dataset and look them up.
--EDIT-- I incorrectly linked to the COBOL PC Pricer code above for OPPS! Here is the pricing data: https://www.cms.gov/Medicare/Medicare-Fee-for-Service-Paymen...