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	$153.30	4.676%	$160.4683	$160.47	$160.45	$160.50
Purchase #2	$66.99	10.227%	$73.8411	$73.84	$73.85	$73.80
Purchase #3	$37.87	3.189%	$39.0777	$39.08	$39.10	$39.10
Purchase #4	$243.92	4.356%	$254.5452	$254.55	$254.55	$254.50
Purchase #5	$140.27	11.555%	$156.4782	$156.48	$156.50	$156.50
Purchase #6	$66.86	6.861%	$71.4473	$71.45	$71.45	$71.40
Purchase #7	$231.62	11.415%	$258.0594	$258.06	$258.05	$258.10
7 purchase totals =	$940.83		$1,013.9172	$1,013.93	$1,013.95	$1,013.90