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	$195.89	5.463%	$206.5915	$206.59	$206.60	$206.60
Purchase #2	$98.28	6.331%	$104.5021	$104.50	$104.50	$104.50
Purchase #3	$39.59	13.119%	$44.7838	$44.78	$44.80	$44.80
Purchase #4	$167.30	13.824%	$190.4276	$190.43	$190.45	$190.40
Purchase #5	$134.81	9.573%	$147.7154	$147.72	$147.70	$147.70
Purchase #6	$163.50	3.698%	$169.5462	$169.55	$169.55	$169.50
Purchase #7	$240.38	6.104%	$255.0528	$255.05	$255.05	$255.10
7 purchase totals =	$1,039.75		$1,118.6194	$1,118.62	$1,118.65	$1,118.60