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	$43.72	7.262%	$46.8949	$46.89	$46.90	$46.90
Purchase #2	$148.70	13.749%	$169.1448	$169.14	$169.15	$169.10
Purchase #3	$231.89	11.565%	$258.7081	$258.71	$258.70	$258.70
Purchase #4	$206.98	3.123%	$213.444	$213.44	$213.45	$213.40
Purchase #5	$51.88	8.719%	$56.4034	$56.40	$56.40	$56.40
Purchase #6	$223.31	6.772%	$238.4326	$238.43	$238.45	$238.40
Purchase #7	$207.89	8.599%	$225.7665	$225.77	$225.75	$225.80
7 purchase totals =	$1,114.37		$1,208.7943	$1,208.78	$1,208.80	$1,208.70