[Tao3300]

That's an IHS with the letters imposed on one another. It's short for 'ihsous', Greek for Jesus.

[wheels]

Fun fact: the actual "dollar" sign is actually a P and an S superimposed, as it's actually a symbol for "peso".

[ahazred8ta]

The superimposed IHS: https://www.istockphoto.com/vector/ihs-ancient-medieval-chri...

And actually the dollar sign started out as two pillars with ribbon banners wrapped around them in an S shape, not as a P-S.