For Categorical Variables
To add subtotals to a categorical variable, go to the variable properties menu and click the Headings and Subtotals button.
Add a new subtotal by clicking the plus sign (+) where you would like the subtotal to appear, and then drag the categories you would like to include in the subtotal to the grey area to the right of the title. Save the variables to create the subtotal.
For Multiple Response Variables
To add subtotals to a multiple response variable, go to the variable properties menu and click the Subtotals button.
Add a new subtotal by clicking the Create subtotal button, and then give your new subtotal a name. Drag in the categories you want to include in this subtotal, and then click Done. Categories you no longer want to include can be removed by clicking the small "x" icon which appears upon hover over each category in the drop-zone.
Unlike with categorical variable subtotals, the subtotals created for multiple response variables are regular categories just like the others, and when you save your changes you are creating a new, additional, variable in the dataset. You will therefore always be prompted to give this new variable a name and an alias, though you can typically just accept Crunch's suggestions for each of these.
Previously created multiple response variables with subtotals can be edited by returning to the properties panel for that variable and re-entering the "Subtotals" interface, where you can add new subtotals, delete existing subtotals, or make edits to the categories included in subtotals.