I don't know if this is even possible today. Can you throw things off of the CN tower still today or is it all hermetically sealed now? Can pennies still kill people at terminal velocity?

I have no response to your actual question; but pennies won't kill someone at terminal velocity (25 mph or so). plus there isn't much mass behind it, and it's a flat disc, so it's not likely to fall straight down anyway (generally lowering the speed as it tumbles)

Didn't mythbusters measure a penny's terminal velocity?

I went a few weeks ago. There's an "outside" section, but it is almost all glassed in, with a bit of fine mesh far from where you can reach.

They did. Their conclusion was that a penny would hurt a lot, but not injure.

Was there ever not mesh or some sort of barrier? I feel like even when it was built someone would have brought up the dangers of someone tossing something, or themselves.