In part, it depends upon the nature of your business, and the terms of the agreement you have with the customer.
If I'm doing work T&M, I will have a figure on my worksheet for "shop supplies."
Distant jobs will have a 'travel charge,' stipulated in advance.
Charges for rentals, subbing to other trades, etc., will be spelled out in most cases.
Communication, and trust, is critical. It is too easy to undermine a relationship by presenting a bill far in excess of what the customer is expecting. I need only think back to the $29 tire that cost me $75.... I haven't been back there since (even though other shops were selling similar tires for $75, at last they didn't post a 'low' price!)
