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	$111.39	6.713%	$118.8676	$118.87	$118.85	$118.90
Purchase #2	$8.76	9.320%	$9.5764	$9.58	$9.60	$9.60
Purchase #3	$131.82	12.746%	$148.6218	$148.62	$148.60	$148.60
Purchase #4	$232.49	10.308%	$256.4551	$256.46	$256.45	$256.50
Purchase #5	$245.50	6.774%	$262.1302	$262.13	$262.15	$262.10
Purchase #6	$59.45	5.379%	$62.6478	$62.65	$62.65	$62.60
Purchase #7	$77.96	10.599%	$86.223	$86.22	$86.20	$86.20
7 purchase totals =	$867.37		$944.5219	$944.53	$944.50	$944.50