Dear Aniket,
For more clarity regarding the basis of rounding off of service for the calculation of gratuity, you can refer to Section 4(2) of the Payment of Gratuity Act, which envisages that "4(2) For every completed year of service or part thereof in excess of six months, the employer shall pay gratuity to an employee at the rate of fifteen days' wages based on the rate of wages last drawn by the employee." In your case, the part in excess of six months is 6 months and 12 days, and hence it would be treated as a completed year.
Regards,