Theoretical Approach - %age of profit from the country
I wonder if one way to attack the problem is to take all of a given conglomerate's financial reports into account as follows:
* US Parent Company reports total gross profit of $30B for a financial year (pre EBITDA)
* US Parent Company reports "$Country operations were fantastic" in producing 10% of turnover (probably hard to enforce/deduce - you'd need SEC etc to require this - but that doesn't sound impossible to get happening)
* Resulting deemed profit for taxation purposes is $3B for $Country at $Country tax rate, less only purely in-$Country costs (i.e. no overseas transactions - this is hard to enforce too)
I know there are wrinkles and problems there, and it wouldn't be easy to police (I'm sure the first thing $corp would do is set up several dozen "arms-length" suppliers to whom it pays $X, and who buy "stock" from $corp at 99.99% * $X). It would permit a company making that $3B of profit to still deduct its local expenses before paying tax on the final "local profits". It lets local businesses (who employ other people who spend money, generating the economy!) compete on a more level playing field.
It takes all the actual real costs to the business into account and taxes only (approximately) the profit created by a given country. Faked ... er, I mean, totally legitimate real reasonable expenses for "IP Rights", "Redistribution Rights", "Marketing", "Support", "Brand Awareness" etc are all taken into account before taxation occurs (in each country). And on the surface it seems like the tax burden in a given country would be ... if not perfectly aligned, at least close to the level of profit. Which ensures that the corp is paying the taxes that, for example, build roads and provide public transport which allow people to get to their stores and buy their stuff.
I'd be interested to hear all the holes that no doubt exist in this approach too :)