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	$50.29	8.859%	$54.7452	$54.75	$54.75	$54.70
Purchase #2	$194.66	10.314%	$214.7372	$214.74	$214.75	$214.70
Purchase #3	$150.86	4.499%	$157.6472	$157.65	$157.65	$157.60
Purchase #4	$147.71	5.764%	$156.224	$156.22	$156.20	$156.20
Purchase #5	$46.40	13.642%	$52.7299	$52.73	$52.75	$52.70
Purchase #6	$56.40	6.179%	$59.885	$59.89	$59.90	$59.90
Purchase #7	$27.95	5.433%	$29.4685	$29.47	$29.45	$29.50
7 purchase totals =	$674.27		$725.4370	$725.45	$725.45	$725.30