EVERY time you pay for something at the store and get change, save your $5 notes.
Put it away somewhere. Don't spend it. At the end of each month, deposit your hoarded fives into a separate bank account.
Journalism professor Marie C. Franklin, who champions the idea on her blog "Save Money Fast With Fives", has saved nearly $50,000 ($US40,000) by following this rule for the past 13 years.
Franklin said she first came up with the idea while putting two daughters through college and struggling to balance the family budget. "I made a decision that forever changed my relationship to money," she wrote.
"Every time someone handed me a five-dollar bill I hid it away. I refused to spend it under any circumstance and started accumulating those fives, first in a separate compartment of my wallet, and then, as the pile grew, in an envelope.
"As the $5s started adding up, I put them in a separate bank account. Within weeks, I had a nice little stash, more than $200. Then $350. Then $500. By the end of the first year, I had saved almost $2000."
She points out that $5 every day for a year works out to $1825 - two $5s and you're looking at $3650. "Save five bucks a day until you turn 75 years old, assuming you're 25 years old today, and that five dollar account, without adding in any
compounded interest if you kept the money in a piggy bank, would be worth $91,250," she writes.
And yes, obviously it means you need to start paying for things in cash. For millennials used to a cashless existence, that means shaking things up.
"You may love the idea of saving your nest egg with $5 bills but unless you use cash on a regular basis for everyday purchases like groceries, food or coffee to go, even gas and other issues of commuting and transportation, it will be impossible to save a significant amount this way," she writes.
"Only cash will do the trick. End of story. Go to the ATM. Take out enough cash to cover the basic expenses you expect to face in the next seven days. Pay for as many things as you can in cash.
"Consume as you need, rather than simply buying out of habit. See how many $5s you get back in a week. If you like the number, repeat it into week two, then a third. At the end of the month, add it up."
If you want to speed things up, she recommends a number of tricks to maximise your $5s, including paying for purchases less than $5 with a $10 or $20, or asking for two $5s instead of a $10 when getting change.
Others have found success with the $5 trick. Writing on Reddit, one user said they saved $2285 in five years, while another said they saved $1500 in six months.
"Working at a pizza shop and collecting tips I knew it'd be perfect," wrote another. "From May to August of this year, I tried to bring home as many fives as I could. [In] mid-August, I cashed in all my fives and had over $525! Very easy way for anyone to start saving money."