Because the phrase ‘by the penny’ is implied that whatever it is, will squeeze all the value out down to the singular digit, because the penny has a value of 1 cent as we all know. However, with the penny no longer in production, how soon can we expect a time where nobody will say “by the penny”?
I don’t even really recognize that unless like down to the penny as in being exacting.
Theres a game on The Price is Right tv show called “To The Penny”.
oh i have not watched that in decades.
I think that’s exactly what OP means. If English isn’t their first language, prepositions do be confusing.