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	$196.87	9.428%	$215.4309	$215.43	$215.45	$215.40
Purchase #2	$162.86	12.417%	$183.0823	$183.08	$183.10	$183.10
Purchase #3	$221.52	5.429%	$233.5463	$233.55	$233.55	$233.50
Purchase #4	$48.37	13.237%	$54.7727	$54.77	$54.75	$54.80
Purchase #5	$203.93	5.638%	$215.4276	$215.43	$215.45	$215.40
Purchase #6	$205.30	3.501%	$212.4876	$212.49	$212.50	$212.50
Purchase #7	$67.83	7.583%	$72.9735	$72.97	$72.95	$73.00
7 purchase totals =	$1,106.68		$1,187.7209	$1,187.72	$1,187.75	$1,187.70