Separate rolls can't interact with each other, so you can't make a roll and add it up after the fact, but if you're OK with
mousing over a result to see the breakdown, you can group separate rolls
within an Inline Roll ie: [[ {1d20, 1d20, 1d20, 1d20} ]] which might display as a single totaled value like 52 , but displays the rolls like {1d20,1d20,1d20,1d20}= {(5)+(15)+(14)+(18)} when you mouse over the total If you're GM'ing, you could certainly use the API to do each roll, assign it to a variable, display the variables, and then add them up and display that. Also, there may be a more graceful way to do this if you're using a particular Character Sheet.