You can do a lookup returning multiple values by providing true at the end of the formula. So given that each employee only occurs once in your list, you could get the max-total-sales  this way using two lookups:

This will give you the person with the highest "totalSales" value in "your-list". I had to work in a filter for the inner lookup to look at only "active" elements as you can´t do lookups without a filter. 

Outter lookup is responsible to get a person filtered by totalSales

Inner lookup gets the highest totalSales number.

Hope this helps!