A box plot shows how values spread, not just their total. The line in the box is the median, the box covers the middle half of the values (from the 25th to the 75th percentile, the hinges), and the whiskers reach out to the data within 1.5 times the box height (the IQR). Marks beyond the whiskers are outliers.
In Tableau a box plot sits on top of individual marks. Put the thing you count on Detail (customers, trips) so each one becomes a circle, put the measure on an axis, and add a box plot from the Analytics pane or with Add Reference Line > Box Plot. Choose Per Cell to get one box per category.
Box plots answer questions totals cannot. A region can have the highest total sales just because it has the most customers, while another region's typical customer spends more.