Let's make these a little more interesting. You can also use any paper but these are sized well for this and people like to be gifted money.
Fold in 1/2 lengthwise
Fold in half to create a crease in the middle.
Take the corner and fold towards you and line up on crease.
Do the same with the other side.
Flip it completely over. Should look like this.
Fold the end down to make a square.
Fold the corner of the square to make a flush triangle.
Repeat on other side. Should look like this.
Fold the triangle up on both sides.
Should look like this.
Do the exact same for both bills.
Tricky part. Lay one on top of another resembling a star. You're going to tuck in the corner in two places.
Tucking in corner.
Tuck in 2nd corner.