$6 is a rather odd amount to put in every time.
On the account that the couple in the story are Mexicans, I'm going to guess that they put in "100 Pesos" every time, and the $6 is just a lazy forex calculation done by the reporter/staff writer.
There's that old joke about putting a coin in a bottle every time you have sex for the first 5 years of marriage, and you take one out every time after that, and the bottle is never emptied.
