The system will automatically join popular tags to the left side of the title in the rendered HTML
<title></title> element - this is done specifically for SEO and delivering more useful titles in search engine result listings.
It's therefore good to avoid deliberately adding tag words in titles, but don't break good composition purely for the sake of avoiding or including one. Here's an example:
How do I tell if a taxi turned on its meter in The Philippines?
That's obviously going to have philippines attached to it, and reiterated in the title, but it's a good title.
Philippines: How do I know if a taxi turned on its meter?
.. That's bad. You're just duplicating what the engine selectively does, and it does a very good job of picking the right tag to join in the title.
How do I know if a taxi turned on its meter?
.. Also bad, because depending on how folks read, they don't know if it's a question they can or can't answer.
How do I know if a taxi turned on its meter in Manila?
Along with philippines - that's the best combination. Get to the specific point as quickly as you can, you've avoided tags in titles, and now there's two locations associated with your question.
In short, don't write for SEO - let the system do it, just write titles that grab the attention of the folks likely to be able to answer the question.