Make a dollar coin, the size of a current-half-dollar.

Make a half-dollar coin, the size of the current quarter.

Make a quarter, the size of the current dime.

Get rid of all other coins. Also remove the $1.00 bill.

Start using $2.00 bills (as smallest cash) and stock ATMs with $50 and $10 bills.

Create a new $1000.00 note.

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[not actually] fun fact: removal of the penny results in more nickels being minted, which will actually result in a net-cost for removing penny from circulation.