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	$223.64	9.634%	$245.1855	$245.19	$245.20	$245.20
Purchase #2	$242.78	13.763%	$276.1938	$276.19	$276.20	$276.20
Purchase #3	$234.67	8.826%	$255.382	$255.38	$255.40	$255.40
Purchase #4	$175.26	13.854%	$199.5405	$199.54	$199.55	$199.50
Purchase #5	$38.35	13.552%	$43.5472	$43.55	$43.55	$43.50
Purchase #6	$125.42	4.813%	$131.4565	$131.46	$131.45	$131.50
Purchase #7	$39.41	8.765%	$42.8643	$42.86	$42.85	$42.90
7 purchase totals =	$1,079.53		$1,194.1698	$1,194.17	$1,194.20	$1,194.20