I agree with the responses. It is confusing, since the strike temperature is given and the mash temperature that you are striving to achieve are given. Then you get the sparge temperature at 168 degrees F. I realized right away that it couldn't be correct, since all of the books I've read say that you should aim to bring the temperature of your grain up to 168 degrees F. with the sparge water.
I tried doing the calculations, based on the grain bed temp at the time I added the sparge water to try and figure out what temp the sparge water had to be to reach 168 degrees F. However, I soon realized that my grain bed temp tended to fall to rapidly after collecting my first runnings, so that by the time I zeroed in on my sparge water temp, it needed to be near boiling.
I've since started heating my sparge water up to boiling while my mash is occurring. I then using a big pitcher and ladle about half of my sparge water into my HLT to preheat it. The other half of my sparge water is still being heated in my boil pot. I'll then drain some of the HLT back down into my boiling sparge water in the boil pot and ladle more up into the HLT, until it holds a temperature at right where I want it to hold at (say 185 degrees F. for my most recent recipe). I repeat this until I hit my target sparge water temperature.
I tried figuring out what my HLT heat loss was, so that I could just heat to a certain temperature, add it to the HLT and have it settle at the proper temp (once again, say 185 degrees F.), but I found that my heat loss was too great if the temperature (of the plastic) was too low in the HLT (I use a coleman cooler) and it wouldn't even get up to my sparge water temp, even if the water was boiling. I've since went to the preheating routine. If I overshoot my sparge water temperature, I just stir it until it gets to about 2 degrees above my sparge water temp and shut the lid. It will usually settle at my sparge water temp and hold there until I need it.
As soon as I'm finished draining my first runnings, I open the valve on my HLT and quickly drain it into my Mash Tun. Stir well, take a temperature reading and close it up to retain the heat. Usually I'm right about 165 to 168 degrees F. now, which is plenty close enough for me.
One thing that is important, is to have a pretty good idea of what your grain temperature is after you've drained your first runnings, so that you can run the calculations as to what your sparge water needs to be at. If you're off on what your grain bed temperature is right after your done draining your first runnings, you'll miss your sparge water temperature. I've learned that if I am on the ball, my grain bed has usually dropped about 5 degrees (your system may be quite different than mine). So, if I'm mashing at 152 degrees F., I know if I immediately add my sparge water, my grain bed will be at 147 degrees F. usually. If I delay to long (wife came out just then and asked a question, or the phone rang, or the neighbor stopped by to drink a homebrew), I'm screwed. I usually tell them I'm at a critical stage right now and I'll get their beer in a minute, or invite them to get it themselves (they know where everything is (beer, beer glass and bottle opener).
Okay, I've rambled on long enough. This is what I do. **Your results may vary.**