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	$244.78	11.217%	$272.237	$272.24	$272.25	$272.20
Purchase #2	$226.32	3.641%	$234.5603	$234.56	$234.55	$234.60
Purchase #3	$186.83	5.293%	$196.7189	$196.72	$196.70	$196.70
Purchase #4	$144.64	11.505%	$161.2808	$161.28	$161.30	$161.30
Purchase #5	$96.28	8.609%	$104.5687	$104.57	$104.55	$104.60
Purchase #6	$48.48	8.194%	$52.4525	$52.45	$52.45	$52.50
Purchase #7	$184.46	3.580%	$191.0637	$191.06	$191.05	$191.10
7 purchase totals =	$1,131.79		$1,212.8819	$1,212.88	$1,212.85	$1,213.00