I just opened a Roth IRA and will be investing money earned through my job which I have already paid taxes on. Do I have to pay taxes up front on that money again when I invest it in my Roth?
A Roth IRA is a tax sheltered Retirement account. It differs from a traditional IRA in terms of when taxes are paid.
It might help to explain by illustrating the two types of account:
With a Traditional IRA, you can pay money into it (subject to conditions) with money from your payroll without paying your regular income tax on the money (if you do, you can claim it back when you file your taxes). When you take the money out of your traditional IRA (e.g. after you have retired), you pay income taxes on that money (that you deferred when you put the money in). You benefit, because your tax rate when you have retired is likely less than what it was when you were working. The government benefits because the money has probably grown, so you're paying tax on more money (so more tax).
With a Roth IRA, you pay money into it after you have paid payroll taxes on the money. After that point, there are no further taxes. No capital gains tax, an when you take the money out, there is no income tax. zip.