There are just two options when it comes to splitting the bill at the end of a meal: 1.) Throw your card down, split it evenly, and don't think twice; it's all right or 2.) Portion out each person's entrée and drinks, split any shared apps, and then deal with the one person who said they didn't eat any of the first appetizer so they don't want to pay for it.
I try to go for Option 1 as often as possible, especially when I'm in a big group, because Option 2 is my dining-out nightmare. Three hours of scintillating conversation, new friends, and great food are going to come to a screeching halt for at least 15 minutes as you try to activate the rusty part of your brain that uses fractions while you sort out the bill. Then you're going to have to hand the waitress nine credit cards with instructions to charge eight different amounts. It's a recipe for quickly evaporating goodwill, especially when someone inevitably tries to give you cash to cover their portion on your card but didn't factor in tip. I'm getting sweaty just thinking about it.
I've gotten dinner with my friend, who's an accountant, often enough to know that a select few people are not intimidated by a miles-long receipt and can make quick work of one, but when I'm not around those people, I like to use Plates. It's by the same people who made Splitwise, a long-term bill-sharing app that I use with my roommates.
Plates, though, is specifically made for dining out. You enter in the cost of each item, drag and drop it to whoever ordered it (or put it in the middle of the "table" for a shared dish), and then calculate out tax and tip. No one is dependent on your dubious calculations when you're four mimosas deep at brunch, and the whole thing takes about a minute and a half.
If you really want to feel like a power user (or if you want to rack up airline miles on a reward credit card), use Plates to calculate out what everyone owes you, then put your card down and have them Venmo you. Bonus: You won't drive your waitress insane!