Yes you can build it, pull in the required dimensions i.e. Customer's list, Product list and Time.
Add a 'Sales' line item. Make sure that that you include both active and inactive customers as it might be a possibility that the customer might have left in the middle of the year giving some sales numbers(before leaving) for the FY. Write a formula in the Sales line item which will fetch the monthly/yearly sales numbers across geographies.
Anaplan is a tool where you can have multiple workarounds to achieve a similar functionality. The output totally depends upon the input that we provide and the calculations that we do or the logic we build for the desired output.
Mathematical questions leads to an answer, but vice-versa would be illogical.