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	$194.80	5.551%	$205.6133	$205.61	$205.60	$205.60
Purchase #2	$29.60	10.564%	$32.7269	$32.73	$32.75	$32.70
Purchase #3	$46.44	12.822%	$52.3945	$52.39	$52.40	$52.40
Purchase #4	$168.83	4.769%	$176.8815	$176.88	$176.90	$176.90
Purchase #5	$52.73	8.480%	$57.2015	$57.20	$57.20	$57.20
Purchase #6	$62.94	13.545%	$71.4652	$71.47	$71.45	$71.50
Purchase #7	$18.43	10.363%	$20.3399	$20.34	$20.35	$20.30
7 purchase totals =	$573.77		$616.6228	$616.62	$616.65	$616.60