I think you'll need the TOTAL qualifier here, to ignore your Country dimension.
sum(Sale) / sum (TOTAL Sale),
sum(Sale/Rate) / sum(TOTAL Sale/Rate)
If you are using multiple dimensions and you want to ignore Country, but not Branch, use a field list with your qualifier:
sum(Sale) / sum (TOTAL<Branch> Sale),
sum(Sale/Rate) / sum(TOTAL<Branch> Sale/Rate)
Note: I assumed thye you are using a chart with dimension Country here, but this information should be part of your request.
I also assumed more things, like CurrencyCode is a field that has an unambiguous value per Country.
For your next request, please add as many information as possible, this is most easy when upload a simple demo QV application that shows what you want to achieve (i.e. a data model close to your original one and the expected outcome).