I will suggest that you ask a TAX PRO in Maryland about this... If there is an IRS office near you that might be the best place or H&R block or jackson Hewitt in Walmart or a Tax Attorney ... but someone in your state for sure....
Plus One on Art's advice, ask a tax pro. But in general gross sales usually means exactly that - gross sales. It has nothing to do with profits. Its money coming in irrelevant of how much is going out. Your last sentence is also puzzling, what difference is there between "total profit" and "my profit"?
If you are asking here, look into a CPA. IT IS A MUST. You said sales and use. (If you bought your cameras online to avoid state tax, USE tax will get you there and IT WILL GET YOU sooner or later.) But only if you are claming the use of the equipment on your business, and the benefits to do so outweigh not paying use tax on it.
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