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	$53.74	11.299%	$59.8121	$59.81	$59.80	$59.80
Purchase #2	$198.89	5.851%	$210.5271	$210.53	$210.55	$210.50
Purchase #3	$179.41	13.645%	$203.8905	$203.89	$203.90	$203.90
Purchase #4	$242.80	3.861%	$252.1745	$252.17	$252.15	$252.20
Purchase #5	$93.64	11.406%	$104.3206	$104.32	$104.30	$104.30
Purchase #6	$92.27	8.470%	$100.0853	$100.09	$100.10	$100.10
Purchase #7	$214.36	3.863%	$222.6407	$222.64	$222.65	$222.60
7 purchase totals =	$1,075.11		$1,153.4508	$1,153.45	$1,153.45	$1,153.40