Unless you're running a one-man garage sale show, you're probably selling someone else's stuff as well as your own. And unless they've given you permission to take the money for everything (as a compensation for your hard work, of course), you'll have to keep track of individual sales somehow. Even if you've just got a few kids who are selling a couple of items each, you want to make sure everyone gets their fair share. You may already have a good system for doing this, but anyone new or veteran to the garage sale hosting scene can use this advice on how to successfully track your sales.
Drawing simple columns on a sheet of paper is about as easy as it gets. Write each person's name at the top, and as whoever is sitting at the sales table totals up a customer's items, they just write down the price each sold for in the proper column. This system is a little primitive, but it's the most straightforward. Just make sure you've got a backup plan in case the paper decides to blow away on the wind.
You can start the system way before you even put the items out by pricing with different colored tags. Colored dots with the price written on them could work, as would using masking tape with a different color of Sharpie ink for each person. Whatever tagging system you use, you'll need to pull off the tags when someone brings you an item to pay for and stick them to a sheet of paper. At the end of the day, it's a simple task to add up each color and hand out that much money. Granted, not all items will easily relinquish their tags, so you may have to manually write down a few of the more stubborn ones, but this system generally works quite well.
You can start out keeping separate money boxes and making change out of each one, but while this is highly convenient at the end of the day, it's painfully slow to actually total up a customer and make the transaction. If you're having to pull three quarters and a dime out of the first box, two dollar bills and two quarters out of the second box, and some unmanageable amount of coinage change from the third, the customer is going to get impatient with you. If you use separate money boxes, do a "halfway" system -- have one change box, and once the customer leaves, then split the profits into the appropriate boxes.
Creating a worksheet may also work for you, if you want something more complex than just a piece of paper with columns. This is handy if you are getting a percentage of the sales you make for other people; you can write the percentage into an appropriate and convenient box and then total it up later.
Taking the money as you go might be the best if you're doling out profits to your kids. As soon as one of their toys sells, give them the money then and there. You don't have to worry about them bothering you over imaginary debts later, and if there's another sale nearby, they can run off and buy a new toy without having to raid your wallet. This isn't such a convenient method if you're selling for a friend who isn't there, however, so keep track instead for fellow adults.
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