In a pure DQL table you can’t sum across the lines in the table. You can for each line sum stuff from each given file, but not from all the files.
This might change if I ever get around to it, but I’ve been so swamped lately with real life stuff, that it’s not looking very good for the near future.
A very good option using Dataview is to encapsulate your query displaying the various values, within some boilerplate dataviewjs to calculate a line with the total. This approach is show cased in the thread below: