I agree with several other moms...I don't think a gift is necessary at this point. Kids are too spoiled these days and EXPECT to get gifts for everything. As a child I never expected to get a gift (nor did I get any) for different occasions other than my birthday and Christmas.
Instead of a gift, create a special moment for your daughter after graduation. Take a good picture at the ceremony and frame it. Let her pick where to go eat afterwards. That should be plenty.
My daughter will have her pre-k ceremony next year and I don't plan to get her a gift. I'll likely do what I just mentioned above. I want her Graduation from High School to be a big deal and it won't be if there are graduation ceremonies at every level and it seems to be going that way unfortunately.
Hope this helps. Enjoy the ceremony next week!