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	$233.67	5.137%	$245.6736	$245.67	$245.65	$245.70
Purchase #2	$176.97	9.389%	$193.5857	$193.59	$193.60	$193.60
Purchase #3	$221.27	5.322%	$233.046	$233.05	$233.05	$233.00
Purchase #4	$160.70	13.491%	$182.38	$182.38	$182.40	$182.40
Purchase #5	$140.76	11.156%	$156.4632	$156.46	$156.45	$156.50
Purchase #6	$69.32	3.776%	$71.9375	$71.94	$71.95	$71.90
Purchase #7	$126.90	11.838%	$141.9224	$141.92	$141.90	$141.90
7 purchase totals =	$1,129.59		$1,225.0084	$1,225.01	$1,225.00	$1,225.00