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	$125.25	13.429%	$142.0698	$142.07	$142.05	$142.10
Purchase #2	$131.77	8.633%	$143.1457	$143.15	$143.15	$143.10
Purchase #3	$132.43	13.561%	$150.3888	$150.39	$150.40	$150.40
Purchase #4	$227.69	3.510%	$235.6819	$235.68	$235.70	$235.70
Purchase #5	$125.69	4.380%	$131.1952	$131.20	$131.20	$131.20
Purchase #6	$109.75	8.776%	$119.3817	$119.38	$119.40	$119.40
Purchase #7	$120.94	4.639%	$126.5504	$126.55	$126.55	$126.60
7 purchase totals =	$973.52		$1,048.4135	$1,048.42	$1,048.45	$1,048.50