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	$219.69	7.528%	$236.2283	$236.23	$236.25	$236.20
Purchase #2	$44.89	12.816%	$50.6431	$50.64	$50.65	$50.60
Purchase #3	$141.87	4.806%	$148.6883	$148.69	$148.70	$148.70
Purchase #4	$219.74	12.257%	$246.6735	$246.67	$246.65	$246.70
Purchase #5	$138.98	7.109%	$148.8601	$148.86	$148.85	$148.90
Purchase #6	$122.29	7.642%	$131.6354	$131.64	$131.65	$131.60
Purchase #7	$130.84	8.792%	$142.3435	$142.34	$142.35	$142.30
7 purchase totals =	$1,018.30		$1,105.0722	$1,105.07	$1,105.10	$1,105.00