I got curious about where the different brokers were spending and making money, and so I wrote up an analyzer (in powertac-tools/logtool-examples) that captures all the transactions, as well as the hourly bank balance, and dumps it to a simple CSV format file. It separates credits from debits, and as a cross-check I loaded a couple into a spreadsheet to compare the sum of all the transactions with the final bank balance. They match, so I guess it's reasonably accurate.
If you pull down the latest powertac-tools and build the logtool-examples dir (mvn clean test), you can run the analyzer as
The default output is one line per timeslot, with a block for each broker (18 columns). Alternatively you can use the --per-broker option to get one line per broker in each timeslot. Then you can grep out the lines for individual brokers if you want to focus on just one.