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	$214.64	3.277%	$221.6738	$221.67	$221.65	$221.70
Purchase #2	$159.53	4.557%	$166.7998	$166.80	$166.80	$166.80
Purchase #3	$133.77	6.657%	$142.6751	$142.68	$142.70	$142.70
Purchase #4	$228.65	5.560%	$241.3629	$241.36	$241.35	$241.40
Purchase #5	$78.36	4.106%	$81.5775	$81.58	$81.60	$81.60
Purchase #6	$76.75	11.431%	$85.5233	$85.52	$85.50	$85.50
Purchase #7	$158.59	8.271%	$171.707	$171.71	$171.70	$171.70
7 purchase totals =	$1,050.29		$1,111.3194	$1,111.32	$1,111.30	$1,111.40