Sunrise times are not very accurate but they are pretty close to being accurate.
The sunrise times that are on websites and google are not 100 percent accurate because I notice that when I check the sunrise time on Google or other websites it's usually off by at least 10 to 20 minutes on some days.
So it's very close to being accurate but that's okay as it's really just a guess on the computers part.
Also the sunset times are off as well by at least 10 to 20 minutes in some cases.
I've noticed that on some nights the sunset time was accurate within 3 minutes of the sun setting for the night.
I don't rely on the sunset or sunrise times much but it's nice to know sometimes when the sun will set and when the sun will rise.