Calculating Daily Totals based on helper sheets

Hello, 

I am very new to Power Bi but really enjoy it so far. I have a good level of knowledge with Excel pivot tables etc but I want to challenge myself and get to know this software more. 

I created this problem for myself and need some help in scoping how to approach different aspects of it. 

Let's suppose I own a chain of restarurants from which I obtain a report at the end of every day to say how many of different foods we sold. This table would include date, time, name of dish, etc. 

Since there are lets say.. 4 locations, each charging for the same food slightly differently, each site would be assigned under a "group 1, 2, 3 or 4" which would determine what they should be charging for food. 

I would then have another table to keep track of which site belongs to what group - this would simply be "Site 1 / Group 2" etc. 

I would then have a table of the different foods, along with their price for each tier. - "Food 1 / Tier 1: £2.00 / Tier: 2 £2.50" etc. 

So things I would like this to be able to do: Calculate daily totals £ for each locations, based on their Tier which determines their pricing strucutre. 

So overall, it's about using these three tables, one which provides the raw data for site/food made, 2nd table to be used to determine first the group to which the site belongs, 3rd table to then determine the price for each food, and then calcualate daily £ totals. 

Any help would be greatly appreciated.