Well, isn't that just a happy little question! When we round 90 to the nearest 10, it becomes 90. You see, 90 is already a multiple of 10, so it doesn't need to change at all. Just like how every tree in our painting is unique and beautiful in its own way.
Oh, dude, rounding numbers, like, totally takes me back to elementary school. So, 90 rounded to the nearest 10 is... drumroll, please... 90! Yeah, no need to change a thing there. It's already snug as a bug in a rug at 90.
When rounding 90 to the nearest 10, you look at the digit in the tens place, which is 9. Since 9 is closer to 10 than to 0, you round up to the nearest 10. Therefore, 90 rounded to the nearest 10 is 100.