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	$181.79	6.469%	$193.55	$193.55	$193.55	$193.60
Purchase #2	$6.83	12.577%	$7.689	$7.69	$7.70	$7.70
Purchase #3	$71.94	12.347%	$80.8224	$80.82	$80.80	$80.80
Purchase #4	$93.32	7.795%	$100.5943	$100.59	$100.60	$100.60
Purchase #5	$52.98	12.314%	$59.504	$59.50	$59.50	$59.50
Purchase #6	$240.69	4.584%	$251.7232	$251.72	$251.70	$251.70
Purchase #7	$95.64	11.643%	$106.7754	$106.78	$106.80	$106.80
7 purchase totals =	$743.19		$800.6583	$800.65	$800.65	$800.70