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	$196.47	8.126%	$212.4352	$212.44	$212.45	$212.40
Purchase #2	$226.57	10.294%	$249.8931	$249.89	$249.90	$249.90
Purchase #3	$227.68	8.265%	$246.4978	$246.50	$246.50	$246.50
Purchase #4	$196.84	9.777%	$216.085	$216.09	$216.10	$216.10
Purchase #5	$34.34	10.571%	$37.9701	$37.97	$37.95	$38.00
Purchase #6	$144.67	7.181%	$155.0588	$155.06	$155.05	$155.10
Purchase #7	$71.29	9.863%	$78.3213	$78.32	$78.30	$78.30
7 purchase totals =	$1,097.86		$1,196.2613	$1,196.27	$1,196.25	$1,196.30