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	$73.82	4.114%	$76.857	$76.86	$76.85	$76.90
Purchase #2	$163.39	4.510%	$170.7589	$170.76	$170.75	$170.80
Purchase #3	$169.35	13.838%	$192.7847	$192.78	$192.80	$192.80
Purchase #4	$142.48	7.313%	$152.8996	$152.90	$152.90	$152.90
Purchase #5	$227.74	12.364%	$255.8978	$255.90	$255.90	$255.90
Purchase #6	$48.81	10.857%	$54.1093	$54.11	$54.10	$54.10
Purchase #7	$239.64	7.715%	$258.1282	$258.13	$258.15	$258.10
7 purchase totals =	$1,065.23		$1,161.4355	$1,161.44	$1,161.45	$1,161.50