$0.10 is supposedly $1.89 today according to an inflation calculator (1939) -> (2018).

$0.05 (for a soda) using the same site is $0.91. Not sure how the scaling works.

My local Costco still serves $1.50 hot dogs + drink, so I'd only need to eat about 93 hot dogs and drink 93 sodas a year to offset the cost of a membership ;) and break even on 1939 hot dog dollars.