Workbooks doesn't currently support the ability to create a list report that then displays a total.  You can create a report that lists data OR one that shows the totals for sub-sets of your data OR one that shows an overall total.

The quickest way to show an overall total is to tick the Summarise the values checkbox for the column that contains your values, as shown in the screenshot below. (Click to enlarge.)  Notice that you can also use this checkbox to show minimum, maximum and average values.

If you want to show the totals for sub-sets of your data, remember to open the Summarise by tab and choose the field that you want to summarise the totals by.