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	$193.50	3.291%	$199.8681	$199.87	$199.85	$199.90
Purchase #2	$103.95	4.393%	$108.5165	$108.52	$108.50	$108.50
Purchase #3	$58.53	12.263%	$65.7075	$65.71	$65.70	$65.70
Purchase #4	$65.87	10.451%	$72.7541	$72.75	$72.75	$72.80
Purchase #5	$39.36	3.811%	$40.86	$40.86	$40.85	$40.90
Purchase #6	$183.31	8.237%	$198.4092	$198.41	$198.40	$198.40
Purchase #7	$47.81	13.390%	$54.2118	$54.21	$54.20	$54.20
7 purchase totals =	$692.33		$740.3272	$740.33	$740.25	$740.40