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	$146.43	4.335%	$152.7777	$152.78	$152.80	$152.80
Purchase #2	$5.59	3.242%	$5.7712	$5.77	$5.75	$5.80
Purchase #3	$226.37	3.762%	$234.886	$234.89	$234.90	$234.90
Purchase #4	$193.38	8.722%	$210.2466	$210.25	$210.25	$210.20
Purchase #5	$214.62	6.157%	$227.8342	$227.83	$227.85	$227.80
Purchase #6	$131.77	7.397%	$141.517	$141.52	$141.50	$141.50
Purchase #7	$180.60	10.705%	$199.9332	$199.93	$199.95	$199.90
7 purchase totals =	$1,098.76		$1,172.9659	$1,172.97	$1,173.00	$1,172.90