Did he use all five of his notes to pay for his beer? Does a beer cost $5? yes to both!
***** SPOILER *****
Steve goes to the pub with one of each kind of New Zealand banknote:
$5, featuring mountaineer Edmund Hillary
$10, featuring suffragette Kate Sheppard
$20, featuring Queen Elizabeth II
$50, featuring Parliamentarian and Maori advocate Apirana Ngata, and
$100, featuring physicist Ernest Rutherford.
The 37 beers came to the exact total - $185, or $5 each. It must have been happy hour.
Well done to JumpingJacks for the solution, Grip for a lot of the narrowing down, Peter for a key question, and everyone else for playing.