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	$216.81	13.593%	$246.281	$246.28	$246.30	$246.30
Purchase #2	$44.60	8.509%	$48.395	$48.40	$48.40	$48.40
Purchase #3	$112.27	13.489%	$127.4141	$127.41	$127.40	$127.40
Purchase #4	$59.28	5.817%	$62.7283	$62.73	$62.75	$62.70
Purchase #5	$233.61	6.842%	$249.5936	$249.59	$249.60	$249.60
Purchase #6	$113.34	9.266%	$123.8421	$123.84	$123.85	$123.80
Purchase #7	$161.62	13.471%	$183.3918	$183.39	$183.40	$183.40
7 purchase totals =	$941.53		$1,041.6459	$1,041.64	$1,041.70	$1,041.60