1. Make a category for each child, named after the child (for example Emma), and put that child's items in it.
2. Name each item with the product and the child, like Mints - Emma. Use any product names you like (Pixies - Emma, Katydid - Emma) and add as many deals as you want (Two Mints - Emma at $25). Each one gets its own row.
3. Add a donation item for each child, like Donation - Emma, and set its price to variable so you can type the amount at checkout. Anything with a variable price or "donation" in its name counts as a donation, not candy.
4. Turn on tipping if you want to accept extra gifts at checkout. Tips are tracked separately and credited to the child whose items were in the sale.
5. Prices that include the fee are fine (for example $10.45 instead of $10). The dashboard shows the real amount paid, the real fee Square charged, and what's left.

No categories? The dashboard can still tell children apart from item names written as Mints - Emma, Mints (Emma) or Emma's Mints. With only one child, categories and names in items are optional; everything shows under one total.