How to generate subtotals in a report?

Using Report Assistant in Base.
Sorting/Grouping for Column Cost.
No Subtotals and Total for Column Amount.
How to make these Totals?

Add a textbox with Data Field Type “Function”, choose the appropriate field from your table or query, and set Function to “Accumulate”. Set the Range as required. You will find a field name like [AccumulationYourfieldYourrange], which I found can also be typed into formulas. So in order to add German VAT, you could say “=[AccumulationYourfieldYourrange]*1.19”.