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	$184.61	8.152%	$199.6594	$199.66	$199.65	$199.70
Purchase #2	$88.71	4.331%	$92.552	$92.55	$92.55	$92.60
Purchase #3	$183.79	13.351%	$208.3278	$208.33	$208.35	$208.30
Purchase #4	$99.89	5.585%	$105.4689	$105.47	$105.45	$105.50
Purchase #5	$170.76	4.676%	$178.7447	$178.74	$178.75	$178.70
Purchase #6	$200.90	8.140%	$217.2533	$217.25	$217.25	$217.30
Purchase #7	$39.89	11.369%	$44.4251	$44.43	$44.45	$44.40
7 purchase totals =	$968.55		$1,046.4312	$1,046.43	$1,046.45	$1,046.50