Shopping is surprisingly more complex that we realize for many students who are working on life skills math. Staying within a spending limit is one issue. The concept of a running balance is another. In this post, I detail an activity in which a gift card in real life and ones in simulations are used in shopping activities. The purpose is to engage students with spending limits and balances.
Real Life Activity
I provided a student with a $10 gift card to buy a hot chocolate at Barnes and Noble. This experience allowed the student to order, pay, and monitor the balance. At some point the card will not have a balance to cover another drink. Not only does this provide real life experience, it provides an anchor for other instructional activities.
The student identified the price, the tax, the total, and the balance. Then he computed the balance to see for himself how this works.

Simulations in Instructional Settings
In our instructional setting, the student is provided an image of a gift card on a Google Slide and is prompted to buy 1 item at a time. This allows for immediate computation and tracking of a running balance.
In the image below, you can see a prompt for the student reflect on how the balance is computed by referring to the in person experience. I have the student compute on Google Calculator to allow me to record the work.

The running balance is recorded on the Google Calculator image ($18.75 below) and the next item is purchased with a new running balance computed.

Generalization
I am in a position to conduct in person instruction at other settings. Obviously, most teachers do not have this opportunity. My recommendation is to collaborate with a parent to facilitate such activities. For example, if the family is going out to eat, the student can be provided a gift card and allow him or her to choose an item and pay independently. Another possibility is that the parent provides a student an e-gift card to spend during class with the teacher.