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	$188.64	4.182%	$196.5289	$196.53	$196.55	$196.50
Purchase #2	$205.49	3.699%	$213.0911	$213.09	$213.10	$213.10
Purchase #3	$37.70	5.807%	$39.8892	$39.89	$39.90	$39.90
Purchase #4	$218.65	9.142%	$238.639	$238.64	$238.65	$238.60
Purchase #5	$184.38	3.393%	$190.636	$190.64	$190.65	$190.60
Purchase #6	$54.64	4.807%	$57.2665	$57.27	$57.25	$57.30
Purchase #7	$119.32	12.105%	$133.7637	$133.76	$133.75	$133.80
7 purchase totals =	$1,008.82		$1,069.8144	$1,069.82	$1,069.85	$1,069.80