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	$177.95	12.184%	$199.6314	$199.63	$199.65	$199.60
Purchase #2	$138.25	8.780%	$150.3884	$150.39	$150.40	$150.40
Purchase #3	$98.70	13.742%	$112.2634	$112.26	$112.25	$112.30
Purchase #4	$197.35	10.294%	$217.6652	$217.67	$217.65	$217.70
Purchase #5	$80.67	12.142%	$90.465	$90.47	$90.45	$90.50
Purchase #6	$180.91	5.619%	$191.0753	$191.08	$191.10	$191.10
Purchase #7	$93.32	9.716%	$102.387	$102.39	$102.40	$102.40
7 purchase totals =	$967.15		$1,063.8757	$1,063.89	$1,063.90	$1,064.00