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	$33.33	12.381%	$37.4566	$37.46	$37.45	$37.50
Purchase #2	$9.67	8.552%	$10.497	$10.50	$10.50	$10.50
Purchase #3	$247.55	3.383%	$255.9246	$255.92	$255.90	$255.90
Purchase #4	$249.59	4.841%	$261.6727	$261.67	$261.65	$261.70
Purchase #5	$68.50	11.536%	$76.4022	$76.40	$76.40	$76.40
Purchase #6	$195.40	7.800%	$210.6412	$210.64	$210.65	$210.60
Purchase #7	$181.49	7.312%	$194.7605	$194.76	$194.75	$194.80
7 purchase totals =	$985.53		$1,047.3548	$1,047.35	$1,047.30	$1,047.40