Ranking calculation in a table

Good morning,

I have a problem with a calculation. I want to do a PARETO Chart. I used the tutorial at this address : https://powerbi.tips/2016/10/pareto-charting/

But when I do it, it doesn't work beacause some of my Sum Sales are equal and the measures don't work. I let you see on this picture :

As you can see, the last calculations are wrong because the ranking is the same for the two last lines. I give you the formula I used : 

Ranking = RANKX(  'Summary',   'Summary'[Sum Sales])

Cumulative Total = CALCULATE(
    SUM( Summary[Sum Sales] ),
    FILTER( ALLSELECTED( Summary ),
        Summary[Ranking] <= MAX( Summary[Ranking] )
    ))

Total Sales = CALCULATE(
 SUM( Summary[Sum Sales] ) ,
 ALLSELECTED( Summary )
 )

Cumulative Percent = [Cumulative Total] / [Total Sales]

Do you have any idea do correct my calculations please ?

Thank you for your help.