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	$237.84	11.613%	$265.4604	$265.46	$265.45	$265.50
Purchase #2	$158.72	11.699%	$177.2887	$177.29	$177.30	$177.30
Purchase #3	$224.60	7.141%	$240.6387	$240.64	$240.65	$240.60
Purchase #4	$113.52	10.182%	$125.0786	$125.08	$125.10	$125.10
Purchase #5	$39.86	10.568%	$44.0724	$44.07	$44.05	$44.10
Purchase #6	$136.38	10.579%	$150.8076	$150.81	$150.80	$150.80
Purchase #7	$55.53	7.869%	$59.8997	$59.90	$59.90	$59.90
7 purchase totals =	$966.45		$1,063.2461	$1,063.25	$1,063.25	$1,063.30