And then businesses will be carefully pricing every item in order to fuck you out of as much of that $0.10 as they possibly can. All those factions of $0.10 will quickly add up to be multiple $ when purchases involving multiple items are made.
I don't really buy this argument. Yes, many businesses will round up the prices, so you might be paying up to 9 cents more than before for certain items. A few businesses might actually round down to compete, since the different between $1 at one store and $.9 dollars at another store is noticeable to the average customer. Obviously this will not have significant effect on big ticket items, a $500 TV is still $500 with or without the pennies. The place it could have more effect is on small items, for the average consumer, the best example is probably groceries. So let's say you buy 50 grocery items per week, and the price increased an average of 5 cents per item, that's $2.50 extra in your grocery bill. I would argue that's not that significant for most people. Taken over 1 year you pay about $130 than the previous year on groceries. The bottom line is that stores that try to jack up the price because of a change like this would likely be noticed by the customers. If you are suddenly paying 10-20% more for common items, you start to notice, and you might shop elsewhere.
The other side you have to look at are the advanatges. So one less digit means less change you have to carry in your pocket, less change in the cash register, less cost for the government to make the pennies and nickels, etc. So, IMO, the advantages outweigh the disadvantages.