But for civilian jumping, most countries have a minimum legal opening height of 2500 AGL for C or D licence holders (1500ft for display jumps with authorisation of BPA/USPA). Round parachutes have been illegal to jump for decades.
Minor point of clarification for US readers: in the US skydiving is almost entirely self-regulated. There is only FAR Part 105 for actual, governmental regulations, and there aren't very many. You can jump anything you want as a main parachute, including round parachutes. You can jump from any altitude you want. You can deploy your parachute at any altitude you want.
That said, in the US the United States Parachute Association pretty much has a stranglehold on the industry, much like PADI, NAUI and SSI do on the scuba diving industry, another self-regulated sport in the US. If you jump at a USPA affiliated drop zone, and they pretty much all are, you'll be subject to USPA regulations which are much more extensive. But if you can find a willing pilot and some public land (or private land with permission), you can go crazy and do whatever you like within the bounds of Parts 91 and 105.
P.S. I hold a USPA D-license but hate that they call it a "license" since it certainly isn't a government issued document.