I don't use beersmith, but I suspect it's the same as promash. Calculating the sparge water (for batch spargers) is the same as calculating the strike water. The only difference is that instead of grain being ~68F, it's close to whatever your mash temp was. The volume will be a little less because the grain will retain some water, but it's not a real issue.
When you make your sparge water 180, what temp does your mash get to? Honestly I don't think it really matters. Raising the mash to 170 does not instantly stop all of the enzymatic activity. It takes heat and time to stop them, so the benefit is negligible there. Assuming you aren't having any problems lautering, there isn't much benefit there either.
When I fly sparge, regardless of the temp of the sparge water, it takes FOREVER to significantly raise the temp of the mash. If I mesh at 154, the temp never gets close to 168 during an hour sparge. At a commercial level, where you are draining hundreds or thousands of gallons of wort, it may be more important. IMO, at a homebrew level it's fun thing to try, but ultimately nothing to worry about (unless you are trying to create a challenge by hitting your numbers).