It would appear your best bet would be to print the recipes if this is an issue, I can't seem to find a way to change the units in the shopping cart either.
also, I imagine you can set the weight at your lhbs to decimals. likely under a "unit" button. then you can use decimals everywhere.
anyways, 8oz is .5, 4oz is .25, 2oz is .125 and every once is .0625, so it shouldn't be terribly complicated to do the math, although personally i normally just round everthing up to the nearest pound (or 5, or a bag) that way I'll have whatever i need on hand later.
if it's base, i buy a bag.
If its a specialty i use in many recipes, i buy 10-25lbs and keep in gamma seal buckets.
if its a specialty i dont use in many recipes, i round up and double, keeping the extra in vacuum sealed bags. this way if i want to do the recipe again i've got it handy.