During the Coronavirus pandemic, I sometimes shopped for other people, and split the costs charging them for the food, and gas.
The prices ended up being really good, because I could shop at a grocery warehouse. This was an actual grocery warehouse, not a store called “Grocery Warehouse”; they supplied Chinese restaurants, and also did cash and carry.
The prices were comparable to bag-it-yourself discount grocers, but the quality of the vegetables was better. If you were making Chinese food, hey, it was the exact place you wanted to go.
To use this spreadsheet, you download it and make a copy. Enter the receipt into the left three columns, so you enter the name, amount, and price.
A cost per unit is computed. Enter each customer’s order, and the sheet will split the costs. and then you prepare your drop offs. This adds up the cost for each person/customer.
I’d add 2 or 3 dollars for gas. Whatever is appropriate. If you want to add in time, do that as well. (For what it was worth, shopping at the warehouse took all of 15 minutes, because of the limited options.)
To use the Google Sheets version, see this link.
If you want to see some gas mileage estimate, check out the car forms.