Glad you asked...
Before attempting to calculate anything you first need to make sure that you have two important figures. The cost of the sales and the revenue generated. Click here for more info http://www.associatedcontent.com/article...
Then again, this answer might help you...
One thing you will want to look at is if you sold some items like your stock. Gross profit probably will not have the expense of doing the trade or the taxes. It is mostly like if you bought is what you made at the end of the day.

