I've been asked by many airlines for proof of onward travel. At least three times I was given a waiver to sign releasing them of liability if I am not allowed entry into the country.
Since this usually works out I don't buy an onward ticket and am prepared to buy the cheapest possible throw away ticket ($30?) while at the airport check in.
David Broadfoot if I could figure out how to do it online I would do it, but if it’s a big headache I’d rather avoid the stress. Too much stress lately...