Revise how deductions are displayed on the checkout page and receipts

[cachob]

As an xPRO user, I would like to be able to see the tax deductions from my purchase clearly.

I would like to see a minus sign on the amounts that are deducted from my purchase, such as discount:

[arslanashraf7]

Initially, my plan was to do this in a single PR along with #2788. But, while working on that I felt that fixing this in that PR would increase its scope unnecessarily and I thought it would be a good idea to do this in a separate PR.