Invoice Management

On the Supplier setup, Invoice Management, I noticed that all the Site names must have the same invoice tolerance set in order for the Tolerance to work, is this correct or are we missing a setup?  Not all our sites at the vendor level are used as a purchasing or invoice site, some are just for tracking, but if we do not set the Invoicing Tab tolerance to the same as the ones used for invoicing, and the invoice is over the amount  ordered, it will go on hold.  Now, if all the sites (even those not used for invoices)