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	$64.59	5.176%	$67.9332	$67.93	$67.95	$67.90
Purchase #2	$169.70	12.247%	$190.4832	$190.48	$190.50	$190.50
Purchase #3	$161.57	4.642%	$169.0701	$169.07	$169.05	$169.10
Purchase #4	$111.83	10.403%	$123.4637	$123.46	$123.45	$123.50
Purchase #5	$85.83	3.832%	$89.119	$89.12	$89.10	$89.10
Purchase #6	$65.49	3.291%	$67.6453	$67.65	$67.65	$67.60
Purchase #7	$199.52	13.295%	$226.0462	$226.05	$226.05	$226.00
7 purchase totals =	$858.53		$933.7607	$933.76	$933.75	$933.70