A custom pricing engine for a Salesforce customer has to be decided by factors with the following hierarchy: State in which the customer is located…

According to the Get Started with Custom Metadata Types unit on Trailhead, one of the use cases for

custom metadata types is to define custom charges for an accounting app. The unit states that “Say

that your org uses a standard accounting app. You can create a custom metadata type that defines

custom charges, like duties and VAT rates. Then you can write some Apex code that calculates the

total amount due for each invoice by using the metadata from your custom metadata type.”

Therefore, a similar approach can be used to maintain the pricing criteria for a custom pricing engine

in Salesforce.