President Barack Obama and Mitt Romney have sparred over tax policy for many months. They have argued over the treatment of the middle class, small businesses and whether the Bush-era tax cuts should be extended for the wealthiest 2 percent. The first presidential debate sparked debate on a different point -- the taxes paid by companies doing business overseas. So far, this topic has not played a prominent role in the campaign, although American-based multinational firms have a huge stake in the outcome. By one conservative estimate, this part of the tax code is worth $30 ...