"Restricted Measure"

There's a few ways to do this.. First - you don't need a measure. If your Amount field is set as a number and set to sum you can get this result:

Second - If you wanted a measure to do this instead you can use

Total Sales = SUM('table'[Amount])

to get:

Third - You can create a measure that will force it to look at only the countries. This will ignore any other fields you add to your table which might make you think your total is incorrect. This is not the case as the measure is explicitly set to use only Country. I would not recommend using this one based on your description of the problem but thought I'd include it if it does help!

Total Sales Country = CALCULATE(SUM('table'[Amount]),ALLEXCEPT('Table','Table'[Country]))

to get:

Hi Anonymous ,

You could try this formula:

Measure =
CALCULATE (
    SUM ( 'table'[amount] ),
    FILTER (
        ALLSELECTED ( 'table' ),
        'table'[country] = SELECTEDVALUE ( 'table'[country] )
    )
)

Best Regards,

Jay