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	$178.89	9.379%	$195.6681	$195.67	$195.65	$195.70
Purchase #2	$165.65	7.150%	$177.494	$177.49	$177.50	$177.50
Purchase #3	$153.89	12.745%	$173.5033	$173.50	$173.50	$173.50
Purchase #4	$100.33	5.181%	$105.5281	$105.53	$105.55	$105.50
Purchase #5	$126.31	12.756%	$142.4221	$142.42	$142.40	$142.40
Purchase #6	$227.34	4.818%	$238.2932	$238.29	$238.30	$238.30
Purchase #7	$29.59	3.560%	$30.6434	$30.64	$30.65	$30.60
7 purchase totals =	$982.00		$1,063.5522	$1,063.54	$1,063.55	$1,063.50