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	$95.67	10.424%	$105.6426	$105.64	$105.65	$105.60
Purchase #2	$15.91	13.111%	$17.996	$18.00	$18.00	$18.00
Purchase #3	$91.82	6.526%	$97.8122	$97.81	$97.80	$97.80
Purchase #4	$47.88	4.197%	$49.8895	$49.89	$49.90	$49.90
Purchase #5	$67.88	4.723%	$71.086	$71.09	$71.10	$71.10
Purchase #6	$155.53	10.245%	$171.464	$171.46	$171.45	$171.50
Purchase #7	$192.39	11.852%	$215.1921	$215.19	$215.20	$215.20
7 purchase totals =	$667.08		$729.0824	$729.08	$729.10	$729.10