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	$222.39	3.661%	$230.5317	$230.53	$230.55	$230.50
Purchase #2	$85.87	3.495%	$88.8712	$88.87	$88.85	$88.90
Purchase #3	$169.76	10.796%	$188.0873	$188.09	$188.10	$188.10
Purchase #4	$28.69	8.632%	$31.1665	$31.17	$31.15	$31.20
Purchase #5	$248.31	9.496%	$271.8895	$271.89	$271.90	$271.90
Purchase #6	$60.38	3.695%	$62.611	$62.61	$62.60	$62.60
Purchase #7	$227.29	11.605%	$253.667	$253.67	$253.65	$253.70
7 purchase totals =	$1,042.69		$1,126.8242	$1,126.83	$1,126.80	$1,126.90