The Transaction Detail report will give you access to every transaction that you have carried out for a particular event.
If you need to go back and trace accounting adjustments you've made, this is the place to do it.
When you click the Transaction Detail report in the reporting menu, you'll see a small dialogue box appear with a few options to help you wrangle this report to your liking:
You can limit transactions to either Attendee or Exhibitor transactions - this will likely be of use if you have both classes of people, given they will be purchasing different items at your event.
With Report Scope, you can either see all transactions for that particular event (which could be daunting), or you can filter by a specified date range.
When you're finished, hit Print Report and you're off to the races!