It's good to help end corruption.
Tom recognizes a disturbing trend in his accounting at work, and it looks like someone is nefariously changing numbers in their financial reporting.
Tom needs to decide what to do about what he has found in the books.
Tom takes his findings to management and records, for his own records, the steps that he took to assure that the issue was reported properly.
Tom pretends that he hadn't noticed the irregularities in financial reports and doesn't mention what he found to anyone else.
Tom is clear of the incident, and he is relieved that he has done everything he can to assure the quality of his work.
When it eventually comes out that there was someone stealing at the company, Tom is implicated in the scandal because he does the books.