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	$210.28	5.732%	$222.3332	$222.33	$222.35	$222.30
Purchase #2	$73.26	7.207%	$78.5398	$78.54	$78.55	$78.50
Purchase #3	$218.79	3.485%	$226.4148	$226.41	$226.40	$226.40
Purchase #4	$87.97	10.869%	$97.5315	$97.53	$97.55	$97.50
Purchase #5	$176.47	11.389%	$196.5682	$196.57	$196.55	$196.60
Purchase #6	$56.62	6.870%	$60.5098	$60.51	$60.50	$60.50
Purchase #7	$190.81	6.717%	$203.6267	$203.63	$203.65	$203.60
7 purchase totals =	$1,014.20		$1,085.5240	$1,085.52	$1,085.55	$1,085.40