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	$106.68	11.315%	$118.7508	$118.75	$118.75	$118.80
Purchase #2	$107.81	3.729%	$111.8302	$111.83	$111.85	$111.80
Purchase #3	$108.64	4.132%	$113.129	$113.13	$113.15	$113.10
Purchase #4	$108.39	4.716%	$113.5017	$113.50	$113.50	$113.50
Purchase #5	$195.90	11.533%	$218.4931	$218.49	$218.50	$218.50
Purchase #6	$173.39	5.514%	$182.9507	$182.95	$182.95	$183.00
Purchase #7	$224.72	11.455%	$250.4617	$250.46	$250.45	$250.50
7 purchase totals =	$1,025.53		$1,109.1172	$1,109.11	$1,109.15	$1,109.20