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	$229.62	8.642%	$249.4638	$249.46	$249.45	$249.50
Purchase #2	$89.27	5.859%	$94.5003	$94.50	$94.50	$94.50
Purchase #3	$244.34	4.588%	$255.5503	$255.55	$255.55	$255.60
Purchase #4	$77.33	10.254%	$85.2594	$85.26	$85.25	$85.30
Purchase #5	$56.65	7.586%	$60.9475	$60.95	$60.95	$60.90
Purchase #6	$223.39	4.512%	$233.4694	$233.47	$233.45	$233.50
Purchase #7	$187.29	3.264%	$193.4031	$193.40	$193.40	$193.40
7 purchase totals =	$1,107.89		$1,172.5938	$1,172.59	$1,172.55	$1,172.70