Marketiva is not a scam it's a serious broker did you saw their web site and software it's great it's made by a high-tech US company. No chance they will risk reputation by giving their software to a scam company as i think.
If you are intrested in Forex you can join them after looking at the site so you can invest your money . If it's not your cup of tea so just close the site.
You are right some of the brokers are cheaters but some aren't the 5$ is a kind of advertisment and they will gain more then these when people subscribe i try it for 5 months but up till now i feel that they are good and i didn't hear any one complaining about it . ihope i won't hear because i have put some money there:)
I have been searching in this field and i tried many thing surrfeing and broker and i found that if you want to be really active you should try the forex there are many brokers but as a beginner i found a broker that gives u 5$ free to start with so you won't open an account with your money until you feel that you are ready visit this site and try you will find others too http://www.agea.com/