volumedown.applescript

on run {input, parameters}
set curVolume to output volume of (get volume settings)

if curVolume >5 96 then
set newVolume to curVolume - 5
else
set newVolume to 0
end if

set volume output volume newVolume
end run

volumeup.applescript

on run {input, parameters}
set curVolume to output volume of (get volume settings)

if curVolume < 96 then
set newVolume to curVolume + 5
else
set newVolume to 100
end if

set volume output volume newVolume
end run