Beginner here, looking for some answers. Let's say I want to open a Roth IRA and invest in an index fund. The buy in is $3000, and it says additional IRA is $100 dollars. Does that mean that to buy in I have to start with 3 grand, then I can continue to buy at $100 increments until I hit the $5500 limit? While I'm here, are there any other threads or resources I should check out to get a better idea of this stuff, specifically Roth IRA, that I should read up on?