Weigh 4.5 ounces, 5.01 ounces, 5.3 ounces 4.75 ounces 4.9 ounces which is the best whole number of estimate of how much all the containers wieigh together

I'd round off all five weights, obtaining {4.5, 5, 5, 5, 5}.  The sum of these five weights is 24.5, which we divide by 5 to obtain the estimate:

24.5
=  4.9.  Round this up to the nearest whole number:  5.  This is "the best         5               whole number estimate of the contents of these 5 containers."