For IRS reporting purposes, you can safely aggregate all of your category-specific itemized deductions and business expenses into single-line entries.
For example, you can add up all of your real estate property taxes paid, or separately all of your monetary charitable deductions, as a single entry for purposes of Form 1040, Schedule A (itemized deductions). Or, you can add up all of your monthly phone bills as single business expense, and make a single line entry, on Form 1040, Schedule C (self-employment reporting).
If your purchases from the same supply company were for different business expense categories, however, such as for both inventory and consumable supplies (copy paper, pens, coffee filters, etc.), then those would need to be made as two separate entries, for tax accounting purposes, on your tax return.
Also, if you purchased consumable supplies, in the same deductible accounting category, from two different companies, A and B, then you can (and should) add up and combine those invoiced amounts from both companies when you enter your expenses on your tax return.
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