There are a number of on-line resources for invoice and MSRP numbers. Edmunds.com, KBB, True Car, etc. Google auto invoice and you will have a variety of options.
There is MSRP, Invoice, and then Hold-Back. Hold-Back is MSRP minus freight times 3%. In addition, there are consumer incentives, dealer incentives, and dealer contests that are continuously changing. Some of those can be found on-line as well but not always. They are limited only by the imagination of the newly minted MBA in charge of promotions, today. They can be either Regional or National.
Contrary to popular myth, there are no yearly bonuses based solely on how many vehicles a dealer buys from the manufacturer. Generally, any short term incentives to purchase are divided into dealer volume categories. The larger the dealer the smaller the price is not true and in some rare cases can be the opposite.