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	$94.82	11.421%	$105.6494	$105.65	$105.65	$105.60
Purchase #2	$130.33	7.489%	$140.0904	$140.09	$140.10	$140.10
Purchase #3	$108.49	4.250%	$113.1008	$113.10	$113.10	$113.10
Purchase #4	$138.86	11.164%	$154.3623	$154.36	$154.35	$154.40
Purchase #5	$100.25	6.258%	$106.5236	$106.52	$106.50	$106.50
Purchase #6	$215.45	8.789%	$234.3859	$234.39	$234.40	$234.40
Purchase #7	$191.89	8.616%	$208.4232	$208.42	$208.40	$208.40
7 purchase totals =	$980.09		$1,062.5356	$1,062.53	$1,062.50	$1,062.50