Count unique days when days have multiple entries

I have daily sales data, and I want to count how many days a given sales person made a sale. However, they could make two sales on a given day, and will therefore have two lines. As a for instance, if someone makes a single sale on each day of March, but on March 31 makes two sales, my function is returning 32. I'm currently using a calculate/countrows function structure, but is there a way to only count the unique values when sales occur? Obviously there aren't 32 days in March, but I don't want to use a min/max function because I only want to give credit for the days with actual activity. Does this make sense? Any help is appreciated.