Sentence (1) is fine with either "a" or "any," the only difference being that "any" is more emphatic.
I don't think (2) is a good sentence for several reasons:
- "metropolitan city" is not a good collocation. We can say things like "metropolitan area" or "big city," but "metropolitan city" is clearly redundant.
- You should say "a 15 percent tax."
- I think "its value" is the normal phrase.
And, last but not least, that sentence does not sound right with "any" because that would suggest an unlikely situation, and we all know that that there are thousands of houses in big cities.