Just a few days ago I posted about BananaBux, a site which had a lot of promise but eventually turned into a scam. And today, it's the turn of A5Bux. Even though the site still exists, but I am very sure that it will follow the steps of BananaBux.
The Admin of A5Bux had disabled payments on the 15th of June, and had promised to open it on the 23rd of the month. Well, he did open it on the 23rd, but only for a limited time, which allowed only a few lucky guys to cashout.
In any case, disabling payouts itself is a huge sign that the site is in a financial crisis, and will soon vanish. The admin is nowhere to be found now, and the forum is full of questions regarding doubts about the payments.
http://www.a5bux.com/forum/

So, it's obvious that A5Bux won't exist for much long.