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	$196.39	6.676%	$209.501	$209.50	$209.50	$209.50
Purchase #2	$125.72	12.616%	$141.5808	$141.58	$141.60	$141.60
Purchase #3	$139.64	12.636%	$157.2849	$157.28	$157.30	$157.30
Purchase #4	$99.35	3.183%	$102.5123	$102.51	$102.50	$102.50
Purchase #5	$129.62	11.668%	$144.7441	$144.74	$144.75	$144.70
Purchase #6	$139.98	12.526%	$157.5139	$157.51	$157.50	$157.50
Purchase #7	$211.39	9.533%	$231.5418	$231.54	$231.55	$231.50
7 purchase totals =	$1,042.09		$1,144.6788	$1,144.66	$1,144.70	$1,144.60