You can find such information in the broker's webpage. For example, if you want to open a ROTH IRA account in vanguard, you can find information at

https://flagship2.vanguard.com/VGApp/hnw/content/AccountServ/Retirement/ATSRothIRAOverviewContent.jsp

Account fees and minimums »

• For most Vanguard funds, a minimum initial investment of $3,000 per fund to open a Roth IRA.
  
• No enrollment, transfer, or advisor fees.
  
• Low expense ratios that vary by fund.
  
• $10 annual custodial fee on each fund in your Roth IRA with a balance of less than $5,000.

If you know the symbol if the fund you want to invest, you can also check in morningstar.com. It covers many brokers.