No, I do not think that tax rates should be set so that they would penalize people who want to get married. Tax rates should actually be lowered for those who get married as a way to stimulate the economy. Holding weddings means that people will buy presents for the happy couple which helps the economy.
No, I do not think that tax rates should penalize marriage, and that people getting married can help to stimulate the economy. Trying to penalize marriage through taxes will hinder the economy, as those who are getting married will boost the economy with buying goods and utilizing services that can help those in the private sector.
If it should do anything, it should be the opposite. I'm not saying that I'm for a tax break for marriage, but if we have to choose one or the other, we should definitely not making a tax penalty for it. Marriage, even in the 21st century, is still a major building block of our society, and it shouldn't be discouraged.
Two individuals have separate households an pay X amount of taxes. They two individuals decide they can tolerate each other well enough to marry. Their taxes should not go from X+X (or 2X, if you like) to 2X+Y. Sharing a household does not mean that you pay any less for most things. You still consume the same amount of food, petrol, power. You may have a tiny break on the base cost, but all in all, your financial situation will remain the same.