It's funny, if Bush just did away with the penny, it might be the one thing his administration did that would be remembered favorably.
The problem though with building the taxes into the cost so that you always came to 5-cent intervals would be this new thing we're doing with "tax free" shopping days. You'd have to instigate a suggested policy on the state level when next one was passed to deal with the rounding issues that would be caused - credit purchases could go with the actual amount (as there's no reason not to let the penny live on digitally), but cash purchases would have the total amount rounded to the nearest 5 cents, say...