Creating a line chart with a dynamic total line

parry2k Thank you so much for your help! Your solution didn't work exactly for my case, but it was very close. With some minor tweaks based on your answer, the issue I was having is resolved. 

Create a measure of Total Sales 

Total Sales = COUNT ( Table1[Region] ) 

Create a measure for Selected Sales to be used in Values of the line chart:

Selected Sales = 
VAR _CurrentAxis = SELECTEDVALUE(Total[Region])

return
IF (  _CurrentAxis  = "Total",
    CALCULATE (
        [Total Sales],
        TREATAS ( ALLSELECTED ( Total[Region] ), Table1[Region] )
    ),
     CALCULATE(
        COUNT(Table1[Region]),
        Table1[Region] = _CurrentAxis
    )
)

EDIT: parry2k did have the correct solution, it was my mistake in copying it over to my own file. Please see their solution

I am creating line chart that shows units sold by location over the period of time. I wanted to add dynamic total line that should shoe total of filtered location units sold and if there is no filter then it should show total units for all location. how can I do that?