When the Viewis not summarized, you need to ensure that totals are enabled for the column - by default a calculated column does not have a summary operation at the bottom. Right-click on the column header and choose Display Total. Then when you summarize, you will get your subtotals.

Note that when desired, you can choose any of the other 3 summary operations (Min, Max or Average) and when summarizing a view, the operation will apply to each summary group.