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	$158.32	10.702%	$175.2634	$175.26	$175.25	$175.30
Purchase #2	$71.69	6.845%	$76.5972	$76.60	$76.60	$76.60
Purchase #3	$89.96	5.758%	$95.1399	$95.14	$95.15	$95.10
Purchase #4	$51.27	3.542%	$53.086	$53.09	$53.10	$53.10
Purchase #5	$157.68	6.602%	$168.09	$168.09	$168.10	$168.10
Purchase #6	$56.27	5.523%	$59.3778	$59.38	$59.40	$59.40
Purchase #7	$190.31	9.429%	$208.2543	$208.25	$208.25	$208.30
7 purchase totals =	$775.50		$835.8086	$835.81	$835.85	$835.90