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	$217.78	4.254%	$227.0444	$227.04	$227.05	$227.00
Purchase #2	$152.79	4.586%	$159.7969	$159.80	$159.80	$159.80
Purchase #3	$167.80	4.212%	$174.8677	$174.87	$174.85	$174.90
Purchase #4	$193.71	11.706%	$216.3857	$216.39	$216.40	$216.40
Purchase #5	$174.87	8.719%	$190.1169	$190.12	$190.10	$190.10
Purchase #6	$102.85	13.229%	$116.456	$116.46	$116.45	$116.50
Purchase #7	$92.52	7.455%	$99.4174	$99.42	$99.40	$99.40
7 purchase totals =	$1,102.32		$1,184.0850	$1,184.10	$1,184.05	$1,184.10