Moral sense

Hello Rabbi,
I work in an accounting firm, a regular job of 9 hours a day.
The method of receiving pay is one in which you enter hours on projects you work on, in other words, if I worked 9 hours a day and only entered 4 hours, I will receive 4 hours of pay and 5 hours will be deducted from my vacation (with pay, but up to the maximum according to the law).
I got to talk to two office mates with different ways of doing things about this: One mate calculates every minute he works and actually only enters hours on projects he worked on during the day, so for example if he went to make coffee for 5 minutes or talked to a friend in the office for 15 minutes, he doesn’t deserve it as pay and is willing to absorb this loss.
 
On the other hand, there is a friend who says that in his opinion, coffee and talking here and there are also part of the work, so he also feeds that into projects. In essence, a situation arises where the client also pays for his coffee break.
The first friend excuses this by saying that his moral sense doesn’t feel right about it, so he doesn’t log hours on it, but the second friend says that he doesn’t think there’s a problem here because there’s no such thing anywhere in the labor market as dedicating all your hours solely to pure work, and coffee breaks and conversation (within reason, in his opinion) are part of the job.
 
I found myself wondering which of the two is right?
And even more so, is the moral sense of one of them too “delicate” or perhaps too “dull”? And of course the overall question of how can I trust my moral sense to tell me what is right to do in a given situation if we see that it varies from person to person.
 
Thank you very much.