Is the field in question a Summary field or a Calculation field? If Summary it should update itself as its referenced data is changed. If it's a calc you may need to force it to update using Commit or Refresh or both.
Actually, take a look at this thread to: Summary field vs Calculation field, especially the post by taylorsharpe.
The running total (summary) was working fine, The issue was if changed the quantity the running total did not register the additional price that was added. I have 3 fields that were working with the cost, my quantity, my price, and then the running total. I couldn't place a calculation field in the price field because how would I enter the original price. I ended up making a subtotal field that is not on the layout, and then the running total gets its info from the subtotal field. Im open to any suggestions that might help streamline this if possible.
It sounds to me as if it might be worth rather than a calc or summary field, using a number field with and auto enter calc set to revaluate (use the Evaluate() function) any time any of its inputs is changed.