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	$233.26	13.205%	$264.062	$264.06	$264.05	$264.10
Purchase #2	$41.95	11.225%	$46.6589	$46.66	$46.65	$46.70
Purchase #3	$196.69	8.738%	$213.8768	$213.88	$213.90	$213.90
Purchase #4	$102.47	9.233%	$111.9311	$111.93	$111.95	$111.90
Purchase #5	$111.74	13.600%	$126.9366	$126.94	$126.95	$126.90
Purchase #6	$217.88	6.326%	$231.6631	$231.66	$231.65	$231.70
Purchase #7	$93.44	6.865%	$99.8547	$99.85	$99.85	$99.90
7 purchase totals =	$997.43		$1,094.9832	$1,094.98	$1,095.00	$1,095.10