title: Subtotals in RDLC report
body: <p>I need to display subtotals in RDLC reports.
  My report should display data like this:</p>
  
  <pre><code>Book            Student           Borrowed
  Book1           John              2
  Book1           Mary              3
  Book1           Bob               1
  
                  Total:            6 --how to do it?
  
  Book2           Alex              1
  Book2           John              7
  Book2           Dan               2
                  Total:            10 --how to do it?
  
  Grand Total:                      16
  </code></pre>
  
  <p>As you see, I have the data grouped by BookName and StudentName. The last column shows how many times the student borrowed that book last year.
  Basically implementing the Grand Total is piece of cake but I can't seem to be able to define a subtotal for each book.</p>
  
  <p>Thanks.</p>