Since I've been called in, this is a bit iffy. In the Republic and early empire, tax farming was essentially blind theft. Tax farmers would bid to the Senate or the emperor, and the highest amount bid was accepted. Then, everything they collected over what they had bid in the province they were assigned to was their profit. This incentivized looting the provinces blind. There were often multiple tax collectors, or publicani, assigned to a province, and they would all seek to collect their taxes regardless of how many others had already done so before them. The system got...vaguely better under Augustus, but it wasn't until the middle empire, when citizenship was given to everyone in the empire and people could actually levy legal claims against zealous tax collectors, that things got measurably better.
Things were different in Rome proper, of course, since the wealth of the empire from all it's looting effectively meant that citizens in the imperial core paid no taxes whatsoever.