http://developer.android.com/guide/practices/ui_guidelines/icon_design_tab.html
According to the above link you have to place tab icons in a drawable-hdpi-v5 folder. Does this mean JUST the tab icons go inside that folder and the other icons for that density go into the drawable-hdpi folder? Or should I just place all icons for that density into the v5 folder?
Every folder with a v5 at the end stands for values, drawales etc. for the API Version 5+ (2.0+) that does not affect the density of a screen. Hdpi stands for high density pixels, that means devices that have a screen with a high resolution would use this drawables. Normal screens would use drawables from the mdpi folder. You can put all high density icon in a hdpi folder and all lower resolution drawables in a mdpi or ldpi folder.
To solve your problem: what version of android are you targeting? Lower than 2.0? Are you planing on to follow the design guidlines that strict, that you might have to need to provide drawables for a under 2.0 version of android? If not you can put all hdpi drawables in the drawables-hdpi folder
I hope I could help.