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	$151.87	11.514%	$169.3563	$169.36	$169.35	$169.40
Purchase #2	$175.43	12.425%	$197.2272	$197.23	$197.25	$197.20
Purchase #3	$101.52	4.285%	$105.8701	$105.87	$105.85	$105.90
Purchase #4	$233.62	4.573%	$244.3034	$244.30	$244.30	$244.30
Purchase #5	$110.80	13.364%	$125.6073	$125.61	$125.60	$125.60
Purchase #6	$131.76	9.636%	$144.4564	$144.46	$144.45	$144.50
Purchase #7	$69.35	13.828%	$78.9397	$78.94	$78.95	$78.90
7 purchase totals =	$974.35		$1,065.7604	$1,065.77	$1,065.75	$1,065.80