vacation and sick time

when setting up vacation and sick time I want to pay my employees 40 hours of sick time and 80 hours of vacation time per 2080 hours worked. Doing the math, sick time accrues at .01923 hours per hour worked and vacation time is double that. When I enter those numbers in q books it defaults to a slightly different number. I understand this happens because of rounding when decimal numbers are converted into minutes and seconds. The problem is that the q books conversion ends up accruing sick time and vacation time at 39.87 hours per year and 79.75 hours per year respectively. How do I fix q books so it accrues correctly?