No problem at all, the Store module can record quantities from 999,999,999 down to 0.000001, and costs from 9,999,999 down to 0.000001, so most products can be accommodated.
Herschel’s windows and reports use a cunning display method called “smart-formatting”. This shows only the number of decimal places needed to accurately portray a number and avoids cluttering up everything with unnecessary zeros. It makes things much clearer and easier to read.