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	$129.42	9.278%	$141.4276	$141.43	$141.45	$141.40
Purchase #2	$139.43	3.519%	$144.3365	$144.34	$144.35	$144.30
Purchase #3	$222.85	10.102%	$245.3623	$245.36	$245.35	$245.40
Purchase #4	$49.37	3.496%	$51.096	$51.10	$51.10	$51.10
Purchase #5	$104.42	5.800%	$110.4764	$110.48	$110.50	$110.50
Purchase #6	$213.90	9.754%	$234.7638	$234.76	$234.75	$234.80
Purchase #7	$119.48	11.751%	$133.5201	$133.52	$133.50	$133.50
7 purchase totals =	$978.87		$1,060.9827	$1,060.99	$1,061.00	$1,061.00