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	$247.38	6.334%	$263.049	$263.05	$263.05	$263.00
Purchase #2	$91.26	10.218%	$100.5849	$100.58	$100.60	$100.60
Purchase #3	$41.35	10.479%	$45.6831	$45.68	$45.70	$45.70
Purchase #4	$170.79	10.854%	$189.3275	$189.33	$189.35	$189.30
Purchase #5	$69.52	6.304%	$73.9025	$73.90	$73.90	$73.90
Purchase #6	$79.68	4.283%	$83.0927	$83.09	$83.10	$83.10
Purchase #7	$174.81	12.271%	$196.2609	$196.26	$196.25	$196.30
7 purchase totals =	$874.79		$951.9006	$951.89	$951.95	$951.90