Questions Day Rates

I feel like I've asked this question before, but I did a search and couldn't find anything... Does anyone have a good solution for charging out day rates to customers AND cost rates for day most of the time - but then sometimes you also need to have hourly rates...

Currently I've got it nicely figured out how to do one or the other with items, but as soon as I try to do both it's no good. I am just trying to work on a new allocation rule (modified) that can handle converting from the item "day" rate to an "hour" rate - but it does get messed up because of decimal rounding.

Cheers