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	$220.93	9.513%	$241.9471	$241.95	$241.95	$241.90
Purchase #2	$92.83	6.718%	$99.0663	$99.07	$99.05	$99.10
Purchase #3	$62.57	6.771%	$66.8066	$66.81	$66.80	$66.80
Purchase #4	$158.37	5.851%	$167.6362	$167.64	$167.65	$167.60
Purchase #5	$19.56	5.224%	$20.5818	$20.58	$20.60	$20.60
Purchase #6	$133.77	4.863%	$140.2752	$140.28	$140.30	$140.30
Purchase #7	$244.54	8.458%	$265.2232	$265.22	$265.20	$265.20
7 purchase totals =	$932.57		$1,001.5364	$1,001.55	$1,001.55	$1,001.50