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	$165.27	5.422%	$174.2309	$174.23	$174.25	$174.20
Purchase #2	$239.84	6.228%	$254.7772	$254.78	$254.80	$254.80
Purchase #3	$44.55	3.611%	$46.1587	$46.16	$46.15	$46.20
Purchase #4	$159.93	11.233%	$177.8949	$177.89	$177.90	$177.90
Purchase #5	$200.67	12.563%	$225.8802	$225.88	$225.90	$225.90
Purchase #6	$42.55	7.506%	$45.7438	$45.74	$45.75	$45.70
Purchase #7	$190.42	4.435%	$198.8651	$198.87	$198.85	$198.90
7 purchase totals =	$1,043.23		$1,123.5508	$1,123.55	$1,123.60	$1,123.60