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	$95.69	10.220%	$105.4695	$105.47	$105.45	$105.50
Purchase #2	$139.42	3.754%	$144.6538	$144.65	$144.65	$144.70
Purchase #3	$30.70	11.327%	$34.1774	$34.18	$34.20	$34.20
Purchase #4	$202.31	4.509%	$211.4322	$211.43	$211.45	$211.40
Purchase #5	$46.27	13.257%	$52.404	$52.40	$52.40	$52.40
Purchase #6	$221.42	3.637%	$229.473	$229.47	$229.45	$229.50
Purchase #7	$238.45	12.728%	$268.7999	$268.80	$268.80	$268.80
7 purchase totals =	$974.26		$1,046.4098	$1,046.40	$1,046.40	$1,046.50