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	$200.69	10.465%	$221.6922	$221.69	$221.70	$221.70
Purchase #2	$53.47	7.747%	$57.6123	$57.61	$57.60	$57.60
Purchase #3	$233.27	11.702%	$260.5673	$260.57	$260.55	$260.60
Purchase #4	$12.25	3.319%	$12.6566	$12.66	$12.65	$12.70
Purchase #5	$200.90	7.171%	$215.3065	$215.31	$215.30	$215.30
Purchase #6	$77.38	11.510%	$86.2864	$86.29	$86.30	$86.30
Purchase #7	$199.76	5.452%	$210.6509	$210.65	$210.65	$210.70
7 purchase totals =	$977.72		$1,064.7722	$1,064.78	$1,064.75	$1,064.90