In all seriousness, how about vendors start pricing products with tax included, rounding to the nearest quarter dollar? Say what you will about movie theatre concession pricing, at least you're not going to walk out of there needing a tub for your change as well as your popcorn.
Sales tax in the US is just ridiculous. I've never understood why they would prefer things that way.
It's a crazy system, but state and local governments are dependent on sales tax revenue so it's impossible to dislodge.
The system in the UK isn't exactly sane either though, as I recall from the fact that everything at Pret is advertised with an "eat in" and "take away" price since the two scenarios are taxed differently. If you say you'll take it away but then change your mind and eat it in, you're presumably in serious (theoretical) trouble.
And then you've got the Australian system which is at least invisible to the consumer but is still annoying and inconsistent to the merchant. It was going to be a consistent 10% applied to everything, but the minor left-wing parties insisted at the last minute that it needed to exclude some but not all forms of food. Meanwhile feminists have been agitating for years to get tampons excluded as well... not because any analogous male or unisex product (toilet paper?) is excluded but because they have apparently run out of any serious problems to complain about.
Since there are sales taxes at multiple levels (another reason - taxes can change frequently and are far from national) having a feel for taxes comes in useful when voting since if you feel you're getting nothing for your local taxes, you can make an informed decision at the ballot box.
Also, something of interest, I have a lot of friends who come over here to Japan and complain at how expensive food is in restaurants. What I noticed is that while the price on the menu is much more expensive than in the States, your final cost is pretty comparative.
US Cocos: ($20 + 10% tax) + 15% tip = $25.30
JP Cocos: ($25 incl. tax, no tip) = $25
I had a Suica card that I bought the first time I went in 2008. I didn't use up all the money that I put on the card and kept it when I came home as a souvenir. When I returned in 2010, I brought it with me, figuring that there was a time limit on the validity of the card, or that I would have to get the card re-activated first. No, it worked just like it did when I bought it in 2008. When it ran out of money, I went to a Suica-issuing ticket machine and put more money on the card. So, don't throw these cards away.
The US, on the other hand, is the most plastic-heavy culture I've visited. It's the only place where it's socially acceptable to pay for a $1.50 cup of coffee with a credit card.
(But you should avoid the Golden Week if you're coming from abroad)
When I buy orsell something of craigslist right now it is almost always cash and the infrastructure available would have to change substantially for that to change.
1. Vending machines
2. Giving change to folks on the street
Also, plenty of people, for whatever reason, pay cash at stores; coins are needed there, of course.
And finally: for better or worse, cash is anonymous. Until a dependable replacement that is also anonymous comes along, people won't switch from cash.
cash is in general, but not coins.