Yes. You know there’s a difference; what you mean is, “how significant is a 0.05 grade point to Ivy League admissions?”
The answer, unfortunately, is higher than you’d like.
On one hand you might say, “3.85 rounds to 3.9—why would anyone care?” And that’s valid. But when you consider what goes into a 3.85 versus a 3.90, then the difference becomes more pronounced.
A 3.9 GPA can be composed of three years of two semesters, each semester containing 5 classes, and all grades equal to As except 3, which are Bs.
A 3.85 GPA is the same but 1 or 2 more Bs.
Now you may say 3.85 rounds to 3.9, but 1 B does not round to 1 A, so there is a difference in mastery of concept of whatever subject.
So we’ve established that there is indeed a difference, and that the difference is likely to work somewhat against you.
But please realize this difference is small and can be overcome in many ways: strong test scores; great recommendation letters from teachers; interesting and well developed extracurricular activities.
So, fear not: you’ve done well and can still achieve your goals.