Saiku has for sometime, supported Totals and recently introduced subtotal support. Totals
To add grandtotals to an axis, click on the drop down arrow in the Axis header to get the context menu. From there navigate to Grand Totals and select the total method you want to use. Subtotals Subtotals are used when you have multiple levels on an axis. To add subtotals create your query then click on the level you are interested in. At the bottom of the popup dialog you will see a subtotals box. Select the totals type you require and press ok.
The result will then be calculated and presented in the query: