Helen, if you have a store there's a pie chart on your invoice and it's got your monthly sales figure next to it in AU dollars, along with the amount of your ebay fees. There's a bit immediately under the pie chart explaining what's included in each figure and what isn't. Any postage labels you printed aren't included in the fee amount, though you can customise your invoices so it's added in if you want.
Any cancelled or unpaid sales are included in the sales figure so you'll have to subtract those to get a true figure. I don't know how far back you can go to see your invoices but it's a lot more than 3 months. I'd prefer to keep my own records for sales anyway but I just write up the fee amount once a month rather than working it for each transaction.
I never post anything without checking my pp account to see that the money is actually in there, and while I'm in there I check the amount of the fee and write it in a column beside the details of the sale. All I have to do is add that column up once a month, along with the total amounts of each transaction. I sell multiples of lower value items but it still doesn't take long to add up. I've been selling off a heap of personal stuff so looking in my paypal account wouldn't help. I sell them on a separate ID to make my bookwork easier.
