You can set upcharges for each item that you offer on the Starchup services page. Find the item you want to add an upcharge to and click the Upcharges button. Add the upcharge and pricing as needed and click Save.  Upcharges can either be a static amount (ie, $0.10), or a % of the item total (ie 5%).

When you Full Detail an item, you will be given the option to add upcharges under the Add-Ons section, where you can select the various upcharges that you wish to add to that order's item. Note that upcharges on Wash & Fold will be added per pound.
You can then edit the quantity and pricing of an upcharge on the digital ticket:

Note: If any customer's preference option has the exact name as an upcharge, that upcharge will automatically be chosen when detailing the relevant item for that customer. For instance, if the customer has chosen Fabric Softener preference "Downy", and the Wash & Fold item has a $.10 upcharge named "Downy", the "Downy" upcharge will be automatically selected.