Continental includes this tax in their ticket price. You must still check in with them at the counter to get your "paid" stamp prior to going through customs and give this to them along with your departure form.
It does one no good to print a boarding pass prior to departure because of this. You must go to the counter and wait in the long line even if you have your boarding pass in order to get you departure tax "paid" stamp.
I learned this the hard way on our first trip. Waited in the long line at customs thinking I was soooo smart to preprint my boarding pass in order to avoid the even longer ticket counter line just to be sent back to the long ticket counter line then back again to the long customs line. I asked the ticket counter lady "what good does it do to preprint your boarding pass here then?" Answer "none":(