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	$117.56	7.227%	$126.0561	$126.06	$126.05	$126.10
Purchase #2	$128.47	3.108%	$132.4628	$132.46	$132.45	$132.50
Purchase #3	$238.83	12.737%	$269.2498	$269.25	$269.25	$269.20
Purchase #4	$10.45	9.638%	$11.4572	$11.46	$11.45	$11.50
Purchase #5	$225.86	5.407%	$238.0723	$238.07	$238.05	$238.10
Purchase #6	$101.69	3.738%	$105.4912	$105.49	$105.50	$105.50
Purchase #7	$121.64	7.832%	$131.1668	$131.17	$131.15	$131.20
7 purchase totals =	$944.50		$1,013.9562	$1,013.96	$1,013.90	$1,014.10