Adding values to show total

Yes, you do this by putting the value you want to display in a Global Variable in Rule Machine. Then you can use a Connector from RM, and use that device in a Decimal Variable tile in the Dashboard. Give the GV an appropriate name, like Total Consumption, and that will show up as the title of the tile. You can do math in a rule to calculate the value to put in the variable.

See this post: