Or if you do land with a steady tailwind and it is within the aircraft limit you don't add any wind correction same for crosswind. The reason you add the correction due to the headwind is in case the headwind component suddenly drops during the approach. if it does drop by half then your IAS will momentarily drop to your vref speed.. ie still safe.
If that happens with the tailwind component it will only serve to increase your IAS which might destabilise your approach but at least you won't run the risk of stalling on short final.