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	$155.39	7.495%	$167.0365	$167.04	$167.05	$167.00
Purchase #2	$124.95	5.189%	$131.4337	$131.43	$131.45	$131.40
Purchase #3	$237.70	11.352%	$264.6837	$264.68	$264.70	$264.70
Purchase #4	$44.32	5.260%	$46.6512	$46.65	$46.65	$46.70
Purchase #5	$150.60	5.742%	$159.2475	$159.25	$159.25	$159.20
Purchase #6	$102.32	9.562%	$112.1038	$112.10	$112.10	$112.10
Purchase #7	$136.53	3.458%	$141.2512	$141.25	$141.25	$141.30
7 purchase totals =	$951.81		$1,022.4076	$1,022.40	$1,022.45	$1,022.40