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	$173.56	8.402%	$188.1425	$188.14	$188.15	$188.10
Purchase #2	$228.37	6.134%	$242.3782	$242.38	$242.40	$242.40
Purchase #3	$126.83	4.712%	$132.8062	$132.81	$132.80	$132.80
Purchase #4	$70.30	5.130%	$73.9064	$73.91	$73.90	$73.90
Purchase #5	$127.72	6.841%	$136.4573	$136.46	$136.45	$136.50
Purchase #6	$177.52	10.704%	$196.5217	$196.52	$196.50	$196.50
Purchase #7	$42.64	4.291%	$44.4697	$44.47	$44.45	$44.50
7 purchase totals =	$946.94		$1,014.6820	$1,014.69	$1,014.65	$1,014.70