When a number is 0, 1, 2, 3 or 4 it rounds down. When a number is 5, 6, 7, 8 or 9 it rounds up. In the case of 617889 the ten thousands digit is 1 so you round down. The answer is 600000.
600000
Oh, dude, 617889 rounds to 600,000 when you're looking at the nearest hundred thousand. So, like, just drop those smaller numbers like they're hot and focus on the big guys. Easy peasy, lemon squeezy.