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	$212.70	4.161%	$221.5504	$221.55	$221.55	$221.60
Purchase #2	$149.43	8.808%	$162.5918	$162.59	$162.60	$162.60
Purchase #3	$29.83	4.109%	$31.0557	$31.06	$31.05	$31.10
Purchase #4	$199.51	5.724%	$210.93	$210.93	$210.95	$210.90
Purchase #5	$72.61	5.363%	$76.5041	$76.50	$76.50	$76.50
Purchase #6	$178.72	8.869%	$194.5707	$194.57	$194.55	$194.60
Purchase #7	$232.53	10.290%	$256.4573	$256.46	$256.45	$256.50
7 purchase totals =	$1,075.33		$1,153.6600	$1,153.66	$1,153.65	$1,153.80