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	$105.33	3.346%	$108.8543	$108.85	$108.85	$108.90
Purchase #2	$232.45	3.793%	$241.2668	$241.27	$241.25	$241.30
Purchase #3	$41.37	6.228%	$43.9465	$43.95	$43.95	$43.90
Purchase #4	$219.74	4.552%	$229.7426	$229.74	$229.75	$229.70
Purchase #5	$154.45	4.491%	$161.3863	$161.39	$161.40	$161.40
Purchase #6	$42.52	6.178%	$45.1469	$45.15	$45.15	$45.10
Purchase #7	$167.29	10.331%	$184.5727	$184.57	$184.55	$184.60
7 purchase totals =	$963.15		$1,014.9161	$1,014.92	$1,014.90	$1,014.90