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	$194.32	5.633%	$205.266	$205.27	$205.25	$205.30
Purchase #2	$225.90	5.139%	$237.509	$237.51	$237.50	$237.50
Purchase #3	$195.37	8.764%	$212.4922	$212.49	$212.50	$212.50
Purchase #4	$144.27	6.111%	$153.0863	$153.09	$153.10	$153.10
Purchase #5	$78.54	6.787%	$83.8705	$83.87	$83.85	$83.90
Purchase #6	$136.75	3.389%	$141.3845	$141.38	$141.40	$141.40
Purchase #7	$117.67	13.241%	$133.2507	$133.25	$133.25	$133.30
7 purchase totals =	$1,092.82		$1,166.8592	$1,166.86	$1,166.85	$1,167.00