The meaning of phrase "common as a ten-dollar bill"

What's the meaning of this idiom?

Context (American English Article - New Insights into Business - Longman, Unit 2):

Besides, with advice on how to land a better job about as common as a ten-dollar bill, many people are learning to play the interview game.


Thanks in advance

It means such advice is very common and easy to find. (A $10 bill is a denomination of US currency.)

"As common as a ten dollar bill" is not a common idiom at all, though, even though the writer's meaning can be understood.

Thank you!