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	$174.61	5.692%	$184.5488	$184.55	$184.55	$184.50
Purchase #2	$10.41	11.456%	$11.6026	$11.60	$11.60	$11.60
Purchase #3	$235.58	12.271%	$264.488	$264.49	$264.50	$264.50
Purchase #4	$212.79	7.624%	$229.0131	$229.01	$229.00	$229.00
Purchase #5	$181.26	10.787%	$200.8125	$200.81	$200.80	$200.80
Purchase #6	$100.39	8.201%	$108.623	$108.62	$108.60	$108.60
Purchase #7	$122.67	4.575%	$128.2822	$128.28	$128.30	$128.30
7 purchase totals =	$1,037.71		$1,127.3702	$1,127.36	$1,127.35	$1,127.30