What is the opposite term for ' accounting' ?

I assume you mean "accounting" as in dealing with financial matters in a proper way, so that the "books" balance at the end of a month or year etc. If that is the case then there is no opposite to "accounting" except to remark on the nature of the financial chaos.

"Discounting" is the act of reducing a price offered, as in "Big discounts on furniture this week only".

Brilliant. You've answered your own question. Every word has to have an opposite. Now tell us the opposite for mathematics, botany, and philately.

It's "Donald Trump cheating on his taxes."

cook the books

The opposite of accounting is definitely not discounting in its usual sense of lowering the price. . Figuratively, "discounting," in the sense of giving less value to a set of facts may have some sense of a difference from accounting, but that would be stretching the meaning with a change of syntax.

"Discounting" the things she said in anger, I think he made an accounting for her behaviour correctly.

I do not think there is a single word meaning the exact opposite of accounting in all senses.
An opposite would depend on the context. Sometimes there would be an opposite for a phrase, such as "There is no accounting for that, " where the opposite of "no accounting for" would be "understanding of."

The opposite of a business with good accounting would be a business without good record keeping.

Grammar Nazi alert: I would say discounting is the closest opposite to the VERB form of accounting, but the reason you are likely a little hazy on this and needed to ask is because your subconscious is like "hey, accounting is also an adjective," which wouldn't have an opposite. You can't be a discounting major. Unless you go to couponing courses I guess? Which, yes, is a thing. Okay, inner monologue stops now for your benefit. Hope it helped.

embezzlement