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	$175.60	5.710%	$185.6268	$185.63	$185.65	$185.60
Purchase #2	$195.90	13.518%	$222.3818	$222.38	$222.40	$222.40
Purchase #3	$11.75	3.346%	$12.1432	$12.14	$12.15	$12.10
Purchase #4	$130.89	5.171%	$137.6583	$137.66	$137.65	$137.70
Purchase #5	$123.82	8.567%	$134.4277	$134.43	$134.45	$134.40
Purchase #6	$19.66	3.245%	$20.298	$20.30	$20.30	$20.30
Purchase #7	$199.45	13.226%	$225.8293	$225.83	$225.85	$225.80
7 purchase totals =	$857.07		$938.3651	$938.37	$938.45	$938.30