Typically you are better off leaving out the tax when posting a deal.
Some states don't even have tax, and others will have different tax.
You can always add a line after your deal that states how much it cost you after tax if you like.
So you can list it as $2. (Mine is better since they are on sale for $3.29 each)
You can edit your post for up to 24 hours. Next to your original post, click the down arrow next to the subject and choose the EDIT REPLY button.
These have been deals on Checkout51 as well, so I personally am going to wait until after midnight tonight to see if they happen to pop back up as a Checkout51 deal..