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	$173.51	13.266%	$196.5278	$196.53	$196.55	$196.50
Purchase #2	$207.78	11.646%	$231.9781	$231.98	$232.00	$232.00
Purchase #3	$100.52	4.458%	$105.0012	$105.00	$105.00	$105.00
Purchase #4	$105.33	13.804%	$119.8698	$119.87	$119.85	$119.90
Purchase #5	$147.49	13.342%	$167.1681	$167.17	$167.15	$167.20
Purchase #6	$31.33	10.443%	$34.6018	$34.60	$34.60	$34.60
Purchase #7	$150.43	11.326%	$167.4677	$167.47	$167.45	$167.50
7 purchase totals =	$916.39		$1,022.6145	$1,022.62	$1,022.60	$1,022.70