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	$201.93	3.360%	$208.7148	$208.71	$208.70	$208.70
Purchase #2	$140.73	11.369%	$156.7296	$156.73	$156.75	$156.70
Purchase #3	$38.56	4.349%	$40.237	$40.24	$40.25	$40.20
Purchase #4	$55.70	6.748%	$59.4586	$59.46	$59.45	$59.50
Purchase #5	$10.81	3.721%	$11.2122	$11.21	$11.20	$11.20
Purchase #6	$28.81	11.318%	$32.0707	$32.07	$32.05	$32.10
Purchase #7	$214.61	3.521%	$222.1664	$222.17	$222.15	$222.20
7 purchase totals =	$691.15		$730.5893	$730.59	$730.55	$730.60