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	$142.58	4.105%	$148.4329	$148.43	$148.45	$148.40
Purchase #2	$81.52	9.279%	$89.0842	$89.08	$89.10	$89.10
Purchase #3	$183.40	6.246%	$194.8552	$194.86	$194.85	$194.90
Purchase #4	$233.94	4.469%	$244.3948	$244.39	$244.40	$244.40
Purchase #5	$182.87	7.300%	$196.2195	$196.22	$196.20	$196.20
Purchase #6	$118.85	8.382%	$128.812	$128.81	$128.80	$128.80
Purchase #7	$39.71	9.831%	$43.6139	$43.61	$43.60	$43.60
7 purchase totals =	$982.87		$1,045.4125	$1,045.40	$1,045.40	$1,045.40