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	$233.26	10.471%	$257.6847	$257.68	$257.70	$257.70
Purchase #2	$76.43	7.608%	$82.2448	$82.24	$82.25	$82.20
Purchase #3	$208.83	6.828%	$223.0889	$223.09	$223.10	$223.10
Purchase #4	$131.91	12.832%	$148.8367	$148.84	$148.85	$148.80
Purchase #5	$94.62	6.187%	$100.4741	$100.47	$100.45	$100.50
Purchase #6	$211.53	13.675%	$240.4567	$240.46	$240.45	$240.50
Purchase #7	$145.48	5.243%	$153.1075	$153.11	$153.10	$153.10
7 purchase totals =	$1,102.06		$1,205.8934	$1,205.89	$1,205.90	$1,205.90