To make it easier on yourself for the future, especially if you're expecting your sales volume to rise significantly, set your preferences to have the invoice data formatted each month for uploading.
Click on the "Account" tab at your Summary page, go to the current invoice and look on the right-hand side. You'll see a blue "set preferences" link which will allow you to choose to automatically have a CSV invoice generated each month. This data can then be uploaded to your computer, and if you're really organized you can set up Excel charts that you can simply dump the data into. Much easier at tax time than trying to re-generate all the figures.
I know you haven't sold too much so far, but if you intend to keep selling, you should be printing or digitally saving each customer invoice for your records. You can always reconstitute sales data from those invoices if need be, and you'll have them handy in case CRA ever requires them. EBay doesn't keep your invoices or sales records forever on their site.
