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	$199.81	7.234%	$214.2643	$214.26	$214.25	$214.30
Purchase #2	$60.35	3.363%	$62.3796	$62.38	$62.40	$62.40
Purchase #3	$111.54	6.671%	$118.9808	$118.98	$119.00	$119.00
Purchase #4	$119.96	10.633%	$132.7153	$132.72	$132.70	$132.70
Purchase #5	$204.97	8.509%	$222.4109	$222.41	$222.40	$222.40
Purchase #6	$79.82	3.519%	$82.6289	$82.63	$82.65	$82.60
Purchase #7	$240.65	8.670%	$261.5144	$261.51	$261.50	$261.50
7 purchase totals =	$1,017.10		$1,094.8942	$1,094.89	$1,094.90	$1,094.90