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	$196.72	8.197%	$212.8451	$212.85	$212.85	$212.80
Purchase #2	$201.37	10.540%	$222.5944	$222.59	$222.60	$222.60
Purchase #3	$85.30	4.143%	$88.834	$88.83	$88.85	$88.80
Purchase #4	$197.85	5.548%	$208.8267	$208.83	$208.85	$208.80
Purchase #5	$233.25	8.601%	$253.3118	$253.31	$253.30	$253.30
Purchase #6	$179.90	9.106%	$196.2817	$196.28	$196.30	$196.30
Purchase #7	$111.77	3.842%	$116.0642	$116.06	$116.05	$116.10
7 purchase totals =	$1,206.16		$1,298.7579	$1,298.75	$1,298.80	$1,298.70