Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$190.39	3.434%	$196.928	$196.93	$196.95	$196.90
Purchase #2	$186.82	5.426%	$196.9569	$196.96	$196.95	$197.00
Purchase #3	$136.83	12.797%	$154.3401	$154.34	$154.35	$154.30
Purchase #4	$66.56	9.390%	$72.81	$72.81	$72.80	$72.80
Purchase #5	$244.46	8.595%	$265.4713	$265.47	$265.45	$265.50
Purchase #6	$249.62	9.483%	$273.2915	$273.29	$273.30	$273.30
Purchase #7	$78.67	5.444%	$82.9528	$82.95	$82.95	$83.00
7 purchase totals =	$1,153.35		$1,242.7506	$1,242.75	$1,242.75	$1,242.80