Yes, but you don't sell it directly to Cuba, you sell it to $COUNTRY which might eventually sell it to Cuba (and you don't even know about it)
It's not you selling to Cuba, it's Cuba buying through intermediates.
(Of course if you really want you can sell things directly to Cuba, but you need to find a way of disguising it)
You're (or, were) also forbidden from bringing Cuban cigars to the US, but if you arrive from a flight from Panama with a box of unmarked cigars nobody is going to do anything.
Except, not really.
You can’t put any app using any encryption technology up on the Google Play Store or the iOS App Store, if you also distribute anything to Cuba.
For the first you need to get an approval from the US DoD, which requires that you never interact with Cuba.