A 10 gallon is too small for any piranha species or any piranha look-a-like species (that includes silver dollars and wimples).
If you can stretch to a 20 gallon, you open your options to this part of the hobby.
You could home a wimple piranha, 3 silver dollars, or even a sole red belly piranha.
Now the thing with red belly piranhas is that they do get big, however they are not particularly active (especially on their own).
I have seen various set ups where people keep a red belly in an uncluttered and well filtered 20 gallon.
However I recon your best bet is a wimple piranha or 3 silver dollars.
Keep a wimple piranha if you want to tell your un-knowledgeable friends you have a pet piranha. Or keep 3 silver dollars if you just want a small shoal of look-a-likes that will patrol the tank and you can keep tank mates with.