I also see it like this: she kept offering to pay her share, and her friend kept saying they'd figure it out later. So later, she split it all evenly, down to the cent. I think this was the friend's way of trying to be as even and as "fair" as possible? I'd really love to hear both sides of this. The truth usually resides somewhere in between.

So, here is the point I think everyone is missing. It isn't paying that is bothering OP, it is the itemized list. It turned everything into more if a business interaction that a trip to see friends. Also, OP said she understood the hotel, rental car, and parking garage fees and she felt that was fair. It was the other stuff, especially since OP payed for dinners and drinks for everyone numerous times while they were out.

Yes and her friend only stayed 3 days, they stayed 10 days. I notice there's no food money for the home included so I think they were hospitable. Also when someone says we'll sort it out later to me, I make sure we do because I don't like putting people out and them having to ask me for my share later it puts them in a bad feeling when they know we agreed and that I should already know I owe them. This guest didn't say a word in reminder and didn't have the cash on her to sort out what they agreed they would later, she had to go to the atm and pointed that out like she had every intention of ignoring what was agreed and never bringing it up. Finally, when you are in a group and one person keeps using their card you know damned well it's because they are the one generous enough to have that card at the ready just to avoid awkward standing around waiting for someone else to offer, they know it wont happen.

Yeah. OP sounds socked, SHOCKED that the shared expenses she offered to split were, in fact, split. The party is the only one that seems questionable, but the rest of it? Makes perfect sense. Each of her "rounding off" examples of how it "should" be coincidentally round in her favor. Her friend is probably sick of it.

I just think asking for them to split the cost of the party they decided to throw for her husband was weird.

The problem is the attitude and method. The hosts took them to places they wanted to show them. They offered to throw the party. The hosts incurred the added costs for things they offered to do without letting OP know the costs were being split. OP would have handled things differently if the hosts had been honest and forthcoming at the outset. Plus a friend of 40+ years comes across poorly giving you a bill that was not expected or even mentioned. The idea of OP paying isn't what they mind. It's the sneakiness and slightly entitled way they went about it. I'd have paid and never spoken to them again. Sometimes paying to learn who are your friends is worth it.

OP paid for meals,but that wasn't taken into account.

And the OP said in comments that their friends had stayed for 3 days only, not 10 days like this trip was. I think there's a lot missing to the story-it wouldn't surprise me if the OP hadn't mentioned money at all and didn't once offer to pay for anything up front, or offer to pay for a meal, or bring them a gift for hosting her, and didn't put their hand in their pocket at any time, and the host simply got annoyed with being used. Calculating to the last penny is either someone who is a scrooge and skinflint, which seems unlikely given they've hosted OP for so long, or someone who is angry, frustrated and aggrieved.

As Franklin is purported to have said, “dead fish and visitors smell the same after three days.”

This is BAD MANNERS - the opposite of HOSPITALITY. When you invite someone, you take on the costs. Most guests will offer to pay something - or even treat you to dinner/outings - one, two- or several nights - for inviting them; but you DO NOT give your guests - people YOU invited to your home an itemized bill. It's creepy and off-putting. Here we are, thinking you're enjoying our company, and you're tabulating everything... Sounds like they're moochers (because they stayed at her house for 10 days without ever offering) and wanted to make some money at their friends' expense!