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	$141.25	6.859%	$150.9383	$150.94	$150.95	$150.90
Purchase #2	$142.44	6.581%	$151.814	$151.81	$151.80	$151.80
Purchase #3	$219.53	3.760%	$227.7843	$227.78	$227.80	$227.80
Purchase #4	$114.74	8.861%	$124.9071	$124.91	$124.90	$124.90
Purchase #5	$87.89	8.140%	$95.0442	$95.04	$95.05	$95.00
Purchase #6	$70.52	11.866%	$78.8879	$78.89	$78.90	$78.90
Purchase #7	$124.88	5.173%	$131.34	$131.34	$131.35	$131.30
7 purchase totals =	$901.25		$960.7158	$960.71	$960.75	$960.60