Ds had to take his first standardized test last year in 3rd grade. We were able to pick from maybe a half dozen approved tests. I ordered it online and ds took it at home. In our state, the results do have to be turned in to the SD. But they don't determine eligibility to continue homeschooling or anything. It's not a pass/fail sort of thing. Maybe they would look twice if a child was slipping significantly lower on the percentages with each test. We have to demonstrate progress and scoring a 10% on a third grade test and then a 10% on a 5th grade test is progress. One can also have the child take the test early enough that there is time to take another one if you feel are unhappy with the results and think it's important (I wouldn't just for the sake of higher scores but would if homeschooling was somehow riding on doing well, but, it doesn't).
Ds did fine on the test. He was grumpy about taking it so he did it in many little pieces over the course of a week (totally allowed under the test directions). Each section is timed but there are many short sections and breaks in between can be as long as you like. He was frustrated with parts and my only goal was getting him to actually do it and not skip sections. I wasn't really concerned with the score, just the getting it done as happily as possible because it was required by law.
Ds was unfamiliar with some things on the test. I did go over some things briefly like different ways to write a math question and when to capitalize letters in a sentence. He did well with most of the language arts section because he has a good vocabulary and I told him to just pick what sounded right for the grammar fill in the blank sections. He was a new reader so he was overwhelmed by the length of the reading comprehension section (2 one page stories followed by questions). I recommended he read the beginning and end of the stories and see if he could figure out the answers from there (because he was really close to refusing to do it at all). That worked well for one story. But the other was a sillier one that was less logical and it didn't work as well for that.
Anyway, if I were you, since it doesn't matter how your kids do, I'd just read a bunch of books or articles about the pointlessness of testing and focus on changing my own attitude towards the tests.