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	$184.50	12.784%	$208.0865	$208.09	$208.10	$208.10
Purchase #2	$128.51	10.347%	$141.8069	$141.81	$141.80	$141.80
Purchase #3	$224.36	8.782%	$244.0633	$244.06	$244.05	$244.10
Purchase #4	$62.83	13.847%	$71.5301	$71.53	$71.55	$71.50
Purchase #5	$90.78	10.582%	$100.3863	$100.39	$100.40	$100.40
Purchase #6	$164.43	12.791%	$185.4622	$185.46	$185.45	$185.50
Purchase #7	$87.74	10.160%	$96.6544	$96.65	$96.65	$96.70
7 purchase totals =	$943.15		$1,047.9897	$1,047.99	$1,048.00	$1,048.10