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	$196.91	6.870%	$210.4377	$210.44	$210.45	$210.40
Purchase #2	$55.28	6.746%	$59.0092	$59.01	$59.00	$59.00
Purchase #3	$127.99	11.281%	$142.4286	$142.43	$142.45	$142.40
Purchase #4	$175.76	5.714%	$185.8029	$185.80	$185.80	$185.80
Purchase #5	$151.94	3.116%	$156.6745	$156.67	$156.65	$156.70
Purchase #6	$198.81	11.843%	$222.3551	$222.36	$222.35	$222.40
Purchase #7	$230.79	9.809%	$253.4282	$253.43	$253.45	$253.40
7 purchase totals =	$1,137.48		$1,230.1362	$1,230.14	$1,230.15	$1,230.10