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	$195.89	7.650%	$210.8756	$210.88	$210.90	$210.90
Purchase #2	$241.31	6.613%	$257.2678	$257.27	$257.25	$257.30
Purchase #3	$180.58	8.811%	$196.4909	$196.49	$196.50	$196.50
Purchase #4	$171.58	10.231%	$189.1343	$189.13	$189.15	$189.10
Purchase #5	$71.83	6.194%	$76.2792	$76.28	$76.30	$76.30
Purchase #6	$50.36	4.215%	$52.4827	$52.48	$52.50	$52.50
Purchase #7	$83.76	6.872%	$89.516	$89.52	$89.50	$89.50
7 purchase totals =	$995.31		$1,072.0465	$1,072.05	$1,072.10	$1,072.10