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	$196.33	9.759%	$215.4898	$215.49	$215.50	$215.50
Purchase #2	$104.68	3.652%	$108.5029	$108.50	$108.50	$108.50
Purchase #3	$104.71	11.829%	$117.0961	$117.10	$117.10	$117.10
Purchase #4	$227.91	8.575%	$247.4533	$247.45	$247.45	$247.50
Purchase #5	$131.70	9.326%	$143.9823	$143.98	$144.00	$144.00
Purchase #6	$108.94	10.130%	$119.9756	$119.98	$120.00	$120.00
Purchase #7	$97.69	3.257%	$100.8718	$100.87	$100.85	$100.90
7 purchase totals =	$971.96		$1,053.3718	$1,053.37	$1,053.40	$1,053.50