For a 5 gallon batch of wine, my understanding is that you use the recipe for a 1 gallon batch of WOW, and times everything by 5, apart from the yeast. So 5 litres grape juice, 5 litres fruit juice, 5 teaspoons of tannin or 5 mugs of strong black tea, 5 times the sugar (if it's 800 grams which I normally add it will be 4kg), and 5 times the rest of the recipe which I can't remember off the top of my head (had a few (many) drinks), but still keep the yeast amount the same.
Whichever WOW you make, it will be extremely dry, but after its been stabalised and degassed, you can back sweeten it to the right sweetness. Depending how dry you like it, you may not need to back sweeten at all.
Just remember that leaving the wine to age to reduce the harshness will affect how much you may want to back sweeten by. I left my last batch of wines maturing for 2 months before bottling and it makes a massive difference to the drinkability of it (I used to bottle it as soon as it was cleared).