Get rid of the repeating fields, these will be a major problem for you for this database project.
Instead, define a table of LineItem records you can relate to your sales order record so that you can list the magazines ordered with one type of magazine one each row of a portal to the LineItem records on a SalesOrder layout. If you have filemaker 11, you can open the invoice starting point template for an example of this table and layout structure.
With that table structure you can create the summary report you want fairly easily.
Here's a tutorial on just such a summary report using just such a design approach: Creating Filemaker Pro summary reports--Tutorial