Actually there is no reason whatsoever to change any of the marked prices of individual items. Where the rounding will take place is at the checkout, where the prices are added up, sales tax applied, and then that total is rounded up or down IF you are paying cash. If you are writing a check or using plastic, the total in odd cents goes in and then shows up on your statement.
Just because there are no longer any pennies in circulation doesn't restrict anyone from paying an amount not an even 5 cent multiple unless you are paying cash. Then its rounded.
[Do your worst. Flame shield in place.] :-)