1. sales.xlsb 

2. customer.xlsb 

• Customers.CustomerID → Sales.CustomerID

= DIVIDE([Total Sales], CALCULATE([Total Sales], ALL(Regions)))

Total Sales YTD :=
TOTALYTD([Total Sales], 'Date Table'[Date])

Sales Last Year :=
CALCULATE([Total Sales], SAMEPERIODLASTYEAR('Date Table'[Date]))

Average Sales Per Category :=
AVERAGE(Sales[TotalAmount])

Running Total Sales :=
CALCULATE(
    [Total Sales],
    FILTER(ALL('Date'), 'Date'[Date] <= MAX('Date'[Date]))
)

Add PivotChart.