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	$208.98	7.825%	$225.3327	$225.33	$225.35	$225.30
Purchase #2	$230.36	10.160%	$253.7646	$253.76	$253.75	$253.80
Purchase #3	$7.47	5.593%	$7.8878	$7.89	$7.90	$7.90
Purchase #4	$99.68	10.223%	$109.8703	$109.87	$109.85	$109.90
Purchase #5	$192.95	11.873%	$215.859	$215.86	$215.85	$215.90
Purchase #6	$163.70	13.262%	$185.4099	$185.41	$185.40	$185.40
Purchase #7	$19.65	10.434%	$21.7003	$21.70	$21.70	$21.70
7 purchase totals =	$922.79		$1,019.8246	$1,019.82	$1,019.80	$1,019.90