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	$203.62	5.760%	$215.3485	$215.35	$215.35	$215.30
Purchase #2	$60.70	11.243%	$67.5245	$67.52	$67.50	$67.50
Purchase #3	$200.79	8.312%	$217.4797	$217.48	$217.50	$217.50
Purchase #4	$201.86	13.187%	$228.4793	$228.48	$228.50	$228.50
Purchase #5	$37.27	13.695%	$42.3741	$42.37	$42.35	$42.40
Purchase #6	$81.95	5.284%	$86.2802	$86.28	$86.30	$86.30
Purchase #7	$167.37	3.723%	$173.6012	$173.60	$173.60	$173.60
7 purchase totals =	$953.56		$1,031.0875	$1,031.08	$1,031.10	$1,031.10