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	$42.87	4.816%	$44.9346	$44.93	$44.95	$44.90
Purchase #2	$239.51	9.156%	$261.4395	$261.44	$261.45	$261.40
Purchase #3	$70.25	12.241%	$78.8493	$78.85	$78.85	$78.80
Purchase #4	$205.64	13.675%	$233.7613	$233.76	$233.75	$233.80
Purchase #5	$148.33	3.438%	$153.4296	$153.43	$153.45	$153.40
Purchase #6	$44.98	10.698%	$49.792	$49.79	$49.80	$49.80
Purchase #7	$195.96	13.733%	$222.8712	$222.87	$222.85	$222.90
7 purchase totals =	$947.54		$1,045.0775	$1,045.07	$1,045.10	$1,045.00