Convert Rank to Customer Count

Hello.

I've been trying to figure out how many customers are buying X% of our products.

In my work in progress file (linked below), I've figured out those customers that purchased 25% of our products are ranked 1 thru 37.  However, because there are ties, there's actually 41 customers in this cohort.  But, I don't know how to write a DAX that shows 41 instead of 37.  

So, because I figured out the rank, I need either a DAX that can:

1) Calculate N customers less than or equal to X% of total

or

2) Calcualte N customers at less than or equal to Y rank including ties

Link

Thanks!