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	$172.61	13.244%	$195.4705	$195.47	$195.45	$195.50
Purchase #2	$65.33	6.755%	$69.743	$69.74	$69.75	$69.70
Purchase #3	$243.57	5.215%	$256.2722	$256.27	$256.25	$256.30
Purchase #4	$48.32	6.504%	$51.4627	$51.46	$51.45	$51.50
Purchase #5	$237.66	3.598%	$246.211	$246.21	$246.20	$246.20
Purchase #6	$133.51	12.755%	$150.5392	$150.54	$150.55	$150.50
Purchase #7	$155.38	4.193%	$161.8951	$161.90	$161.90	$161.90
7 purchase totals =	$1,056.38		$1,131.5937	$1,131.59	$1,131.55	$1,131.60