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	$44.91	7.463%	$48.2616	$48.26	$48.25	$48.30
Purchase #2	$246.99	11.121%	$274.4578	$274.46	$274.45	$274.50
Purchase #3	$143.57	6.470%	$152.859	$152.86	$152.85	$152.90
Purchase #4	$109.66	8.105%	$118.5479	$118.55	$118.55	$118.50
Purchase #5	$229.54	10.592%	$253.8529	$253.85	$253.85	$253.90
Purchase #6	$87.54	4.587%	$91.5555	$91.56	$91.55	$91.60
Purchase #7	$184.29	5.605%	$194.6195	$194.62	$194.60	$194.60
7 purchase totals =	$1,046.50		$1,134.1542	$1,134.16	$1,134.10	$1,134.30