QB stores time in seconds, but allows you to display it in decimal form. So, when you enter a decimal number it converts it to seconds, which rounds it, then it displays it as a decimal based on those seconds.
In your case, you're entering 0.01346, which is 48.456 seconds. So, QB rounds this to 48 seconds, then reconverts it to decimal and the closest five decimal place equivalent to 48 seconds is 0.01333.
0.02833 works out to 101.988 second, and when converted to 102 seconds and then back to decimal, 0.02833 is also the result.
Are you sure these are the right numbers? 48 seconds per hour worked is only 27 hours and 44 minutes for a year of work full time (52 weeks * 40 hours).