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	$209.75	6.131%	$222.6098	$222.61	$222.60	$222.60
Purchase #2	$239.89	5.715%	$253.5997	$253.60	$253.60	$253.60
Purchase #3	$77.46	3.113%	$79.8713	$79.87	$79.85	$79.90
Purchase #4	$10.45	8.120%	$11.2985	$11.30	$11.30	$11.30
Purchase #5	$57.31	11.732%	$64.0336	$64.03	$64.05	$64.00
Purchase #6	$237.91	12.789%	$268.3363	$268.34	$268.35	$268.30
Purchase #7	$153.89	8.314%	$166.6844	$166.68	$166.70	$166.70
7 purchase totals =	$986.66		$1,066.4336	$1,066.43	$1,066.45	$1,066.40