Answer:
Yes you have violated ethical standards
Step-by-step explanation:
The companie's policy is that all expenses must be reported. The taxi fare plus the tip were just $10 but you intend to report $20.
The company policy of not having to give receipt of amounts less than $25 is being manipulated to extort money from the company.
You were involved in a unethical practice where transport fare is reported as $20 instead of $10 for personal gain of the extra $10.