For test 1 (I am assuming, since there are 5 tests), I got 29/30. Most of the signs in the US are used on Australian roads as well, obviously substituting driving on the right with driving on the left, and mph to kmph.
The only one I got wrong was the Speed Limit 50 one, I assumed that it is a max of 50mph in all weather conditions (like it is here in Australia), I didn't know that in the US you can get a ticket for travelling below the posted limit in "adverse weather conditions"; this rule doesn't exist in Australia.