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	$217.64	4.140%	$226.6503	$226.65	$226.65	$226.70
Purchase #2	$8.92	4.516%	$9.3228	$9.32	$9.30	$9.30
Purchase #3	$233.27	9.233%	$254.8078	$254.81	$254.80	$254.80
Purchase #4	$86.57	4.134%	$90.1488	$90.15	$90.15	$90.10
Purchase #5	$220.89	10.259%	$243.5511	$243.55	$243.55	$243.60
Purchase #6	$126.32	8.390%	$136.9182	$136.92	$136.90	$136.90
Purchase #7	$66.58	7.382%	$71.4949	$71.49	$71.50	$71.50
7 purchase totals =	$960.19		$1,032.8939	$1,032.89	$1,032.85	$1,032.90