Item Unit Cost < 0.01

I have a client (running NAV 2009) who has some manufactured goods which have a cost of less than a penny. They sell in orders of several thousand. However, the unit cost was always showing as 0.00. After much searching, I found that I could go into the Item Table (27) and adjust the AutoFormatType to have more decimals. Everything appears to work. However, now I’m worried about possible issues downstream. Does anyone have any experience with this? I don’t wanna create more problems than I solve.