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	$194.53	11.783%	$217.4515	$217.45	$217.45	$217.50
Purchase #2	$208.51	8.257%	$225.7267	$225.73	$225.75	$225.70
Purchase #3	$40.40	8.580%	$43.8663	$43.87	$43.85	$43.90
Purchase #4	$184.74	6.534%	$196.8109	$196.81	$196.80	$196.80
Purchase #5	$162.40	5.657%	$171.587	$171.59	$171.60	$171.60
Purchase #6	$115.43	8.478%	$125.2162	$125.22	$125.20	$125.20
Purchase #7	$99.70	3.849%	$103.5375	$103.54	$103.55	$103.50
7 purchase totals =	$1,005.71		$1,084.1961	$1,084.21	$1,084.20	$1,084.20