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	$210.34	6.806%	$224.6557	$224.66	$224.65	$224.70
Purchase #2	$41.51	5.648%	$43.8545	$43.85	$43.85	$43.90
Purchase #3	$95.45	13.671%	$108.499	$108.50	$108.50	$108.50
Purchase #4	$175.70	10.389%	$193.9535	$193.95	$193.95	$194.00
Purchase #5	$179.69	4.706%	$188.1462	$188.15	$188.15	$188.10
Purchase #6	$100.48	8.565%	$109.0861	$109.09	$109.10	$109.10
Purchase #7	$143.68	3.121%	$148.1643	$148.16	$148.15	$148.20
7 purchase totals =	$946.85		$1,016.3593	$1,016.36	$1,016.35	$1,016.50