For FLH models I typically charge customers for a gallon and a quart of oil ( 3.5 or so for the engine, and a quart + for the primary) Then another quart of gear oil for the tranny. On 99-06 bikes the trannies do not use a full quart (about 22-24 oz) but on 07+ bikes they use a quart and sometime a bit more so it balances out.
I do not know how to justify 7 quarts 
As far as shop supplies go as a shop owner I can understand, but do not agree with, some shops are charging for them. I go through several cans of brake cleaner a week to clean oil that spills when changing filters etc. There are also other cleaners and detail stuff. It all adds up and a shop doing many services can have alot of money spent on these things every month. It is a legitimate expense but passing it on to the customer isn't right in my opinion. To me its a cost of doing business........
It is a cost of doing business, and ultimately you and every other dealer is in business to make money. Fair enough.
The problem is my dealers like you include that cost as part of the regular service cost. So let's say $75 an hour for a 2 hour job costs me $150. So now I go to another dealer who quotes me $65 an hour. Then they add 7.50 for shop supplies and claim it takes 7 qts. to fill the holes because they can't charge partial qts. So now the same job cost me $160 when I was thinking I'd save $10 bucks. So not only do I get screwed, but so do the honest dealers.
So personally, I found a nice honest reliable dealer, and I stick with them. I'm lucky. My closest dealer is one of the best rated in the country. But for those who are not near you or mine.... ARGHHH.
Part of the problem is Harley does the same thing in a way. I bought my wife new wheels for her Street Bob for our anniversary (Romantic aren't I... I swear it's what she wanted). Black Typhoon wheels. Very reasonably priced. Then I get tagged with needing a $100 wheel installation kit. Then I have to buy a different front disk because the one from the old wheel is a different pattern. So those $400 wheels end up costing me $650 for the front and $500 for the back or something like that. Just put the actual f@$#ing price on the damn wheels so I know what it's going to cost me.
Ride Safe,
J-Carr