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	$148.67	3.225%	$153.4646	$153.46	$153.45	$153.50
Purchase #2	$164.29	13.133%	$185.8662	$185.87	$185.85	$185.90
Purchase #3	$217.80	4.554%	$227.7186	$227.72	$227.70	$227.70
Purchase #4	$6.81	11.586%	$7.599	$7.60	$7.60	$7.60
Purchase #5	$122.35	4.205%	$127.4948	$127.49	$127.50	$127.50
Purchase #6	$241.48	12.688%	$272.119	$272.12	$272.10	$272.10
Purchase #7	$99.92	12.566%	$112.4759	$112.48	$112.50	$112.50
7 purchase totals =	$1,001.32		$1,086.7381	$1,086.74	$1,086.70	$1,086.80