you can set the volume steps in gconf "/apps/gnome_settings_daemon/volume_step" there is also a duplicate here https://bugs.launchpad.net/ubuntu/+source/hotkey-setup/+bug/195760
you can set the volume steps in gconf "/apps/ gnome_settings_ daemon/ volume_ step" /bugs.launchpad .net/ubuntu/ +source/ hotkey- setup/+ bug/195760
there is also a duplicate here https:/