It seems like iconed tabs are not used anymore.
You can use a great library I use for tabs (ViewPagerExtentions) which lets you swipe between tabs, and to set icon for every tab, like below:

You need to download the library. In the example project the layout you want is: activity_fixed_icon_tabs.xml
.
It is quite straight forward but if you need any help you can ask me.
If you don't want to get your hands dirty, there is a solution for your problem, provided Here.
Basically you can get to the ImageView inside the tab and call img.setVisibillity(View.VISIBLE)
.
Then he says that in android<3.0 it messes up the tab, but he provides a solution for this also. You can check which android version the device runs, and then do accordingly.
But as I understand, it won't be a problem for you because you want to use the ActionBar
always.
I recommend you to use the ViewPagerExtentions library because it also adds swipe functionallity which is very fancy. But even if you don't want to use this, you have a solution.