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	$148.90	8.108%	$160.9728	$160.97	$160.95	$161.00
Purchase #2	$148.28	6.850%	$158.4372	$158.44	$158.45	$158.40
Purchase #3	$38.97	5.830%	$41.242	$41.24	$41.25	$41.20
Purchase #4	$160.95	5.466%	$169.7475	$169.75	$169.75	$169.70
Purchase #5	$218.46	5.243%	$229.9139	$229.91	$229.90	$229.90
Purchase #6	$90.58	11.385%	$100.8925	$100.89	$100.90	$100.90
Purchase #7	$189.64	11.365%	$211.1926	$211.19	$211.20	$211.20
7 purchase totals =	$995.78		$1,072.3985	$1,072.39	$1,072.40	$1,072.30