I just went through the process of learning CSV import for bills. I've now done this twice, one a batch of around 85 and one a batch of 39 bills. Both times, when I select all of the imported bills, the total differed by $0.01 (one penny) from the total in Excel. And sure enough, in each batch import ONE item was off in QB by one penny from the amount for that line in Excel. I get no error message and the line count is correct.
Now, I was able to find and fix the offending transaction in QB both times. But this behavior does not inspire confidence.