Is it best to use five tags to get the maximum response? If not, how many?
Tags are meant to categorize your question based on what it is about or related to. Members of any SE site tend to follow specific tags based on what they have expertise in or what they want to answer.
Adding the maximum number of tags especially if it has none or superficial relation with your question will only make it counter-productive in the sense you may just reach the wrong audience. This happens frequently in StackOverflow site and only leads to ire.
Of course, if all the tags you wish to add are well related to the question you can add them. But you should choose your tags (1,2, or 5) based on what your question is about.
Why 5? Why not 4 or 3?
It's worth remembering the point of tags is better searchability, and a response is an immediate thing. The use of appropriate tags - especially on SO, where tag filtering is valuable is more important than trying to get a spread of tags, and certainly not to try to get a magical number of tags for best effect. According to a SO developer in the comments, it doesn't affect how it's ranked in the searches either.
More than that - it's worth having a good, to the point title (though, in some cases, one might choose to be clever instead), so someone glancing at a page goes "Oooh, I know this", and having a clear, well written question with any and all appropriate information.
So.. for maximum response, you really need to look at the big picture. I typically actually go for one tag, but I make sure it's a good one. Excessive tags, especially for the sake of tagginess is annoying.