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	$194.77	9.263%	$212.8115	$212.81	$212.80	$212.80
Purchase #2	$75.33	3.372%	$77.8701	$77.87	$77.85	$77.90
Purchase #3	$7.53	11.763%	$8.4158	$8.42	$8.40	$8.40
Purchase #4	$43.43	12.164%	$48.7128	$48.71	$48.70	$48.70
Purchase #5	$241.25	12.802%	$272.1348	$272.13	$272.15	$272.10
Purchase #6	$177.66	10.627%	$196.5399	$196.54	$196.55	$196.50
Purchase #7	$246.41	3.645%	$255.3916	$255.39	$255.40	$255.40
7 purchase totals =	$986.38		$1,071.8765	$1,071.87	$1,071.85	$1,071.80