Percentile Measures in DAX - Errata

In September of last year, I posted two articles on creating percentile measures in DAX. See Creating Accurate Percentile Measures in DAX - Part I and Creating Accurate Percentile Measures in DAX - Part II. About three months after I posted Part I, Richard Mintz left a comment indicating that he was having trouble getting correct results when his data sets had a wide range of values and many duplicates. I haven't been receiving notifications when comments are left, so it's purely by chance that I saw Richard's comment recently.