I decided for the fun of it to run through the block chain and count up all the hash endings to see if any where neglected or if it's fairly uniform and the results I found suggest the distribution is fairly uniform and there is an equal chance of winning with any ending to your transaction.
Code:
Blocks ending in 0 = 14740
Blocks ending in 1 = 15022
Blocks ending in 2 = 15045
Blocks ending in 3 = 14989
Blocks ending in 4 = 14847
Blocks ending in 5 = 14631
Blocks ending in 6 = 14755
Blocks ending in 7 = 14837
Blocks ending in 8 = 14739
Blocks ending in 9 = 14536
Blocks ending in a = 14822
Blocks ending in b = 14688
Blocks ending in c = 14884
Blocks ending in d = 14620
Blocks ending in e = 14787
Blocks ending in f = 14773
236715 Blocks analyzed.
Execution time: 00:06:36.5860377