The Select Country is a back up, in case the Geolocation doesn't get your country right. Like the Australian customer the other day who worked for a US Company with US Servers. He was seeing the ex-GST prices.

No, they don't include the respective Country's sales/import tax, that would be a nightmare.

The prices shouldn't vary; in AUD they are either with or without our GST. Maybe what you are seeing is the exchange rate fluctuation, which I believe changes in real-time.

If you think you are seeing variations, please grab some screen shots and send them through.