The head wobble

Well guys, there something I have to try to explain to you. The Indian head wobble. It makes no sense at all (making it, therefore, very Indian). As far as we can figure out it is the answer to everything. It is a simple side-to-side shaking of the head, like tilting it but not. Either way, we are still trying to figure out how to do it smoothly but are failing miserably.
By answer to everything I mean that if you ask a question (Do you have ____?) they will answer with a head wobble. But it could mean: yes, no, I don't know, maybe, you're welcome, sometimes, no problem, sure, it doesn't matter, or any number of other things. They also do it with as much enthusiasm as we would use to shrug our shoulders at home. It's crazy because you get an answer to your question but you don't know what it means and then have to clarify.
Here's an example of an everyday conversation we have all the time:
"Do you have postcards?" - Head wobble
"So you do?" - Head wobble
"Yes?" - Head wobble
"No?" - Head wobble
"Okay, can we look?" - Head wobble
"Ah, there they are, how much are they?" - 5 Rupees
"Each?" - Head wobble
"Do you sell stamps?" - Head wobble
"No? I have to go to the post office?" - Head wobble
"Which way is it?" - They point in a vague manner toward a general direction
"Okay, thanks" - Head wobble
If there is any difference between a yes and no wobble we are still trying to figure it out. It's just part of the fun though......
Ammon