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	$219.83	9.481%	$240.6721	$240.67	$240.65	$240.70
Purchase #2	$240.25	5.710%	$253.9683	$253.97	$253.95	$254.00
Purchase #3	$196.28	8.143%	$212.2631	$212.26	$212.25	$212.30
Purchase #4	$126.90	13.289%	$143.7637	$143.76	$143.75	$143.80
Purchase #5	$241.32	5.639%	$254.928	$254.93	$254.95	$254.90
Purchase #6	$54.32	8.867%	$59.1366	$59.14	$59.15	$59.10
Purchase #7	$168.32	10.761%	$186.4329	$186.43	$186.45	$186.40
7 purchase totals =	$1,247.22		$1,351.1647	$1,351.16	$1,351.15	$1,351.20