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	$196.72	12.572%	$221.4516	$221.45	$221.45	$221.50
Purchase #2	$7.56	4.339%	$7.888	$7.89	$7.90	$7.90
Purchase #3	$177.74	12.633%	$200.1939	$200.19	$200.20	$200.20
Purchase #4	$55.35	9.438%	$60.5739	$60.57	$60.55	$60.60
Purchase #5	$46.96	3.584%	$48.643	$48.64	$48.65	$48.60
Purchase #6	$172.59	8.274%	$186.8701	$186.87	$186.85	$186.90
Purchase #7	$215.86	12.686%	$243.244	$243.24	$243.25	$243.20
7 purchase totals =	$872.78		$968.8645	$968.85	$968.85	$968.90