How should I report my wife's income from Poshmark sales on a Schedule C?

My wife sells used items via Poshmark for a profit. Since the earnings are reportable income, we're attaching a Schedule C with our return. My understanding of Poshmark's transaction system is as follows:

1. Seller chooses a selling price and lists item.

2. Poshmark allows buyer to purchase at listed price and charges a shipping fee (unknown to seller).

3. Poshmark receives buyer's payment (including shipping charges), pays actual shipping cost, retains a commission on selling price, and credits remaining amount to seller's account.

The seller can see the payments received in her account to determine a total net profit. However, the gross sale amounts, shipping charges, and commissions taken on each sale aren't found in her account history.

Can the payments that Poshmark has made to my wife's account be listed in the "Gross receipts or sales" box of Schedule C, or would we be required to determine the actual gross sales and deduct shipping charges and Poshmark commissions?