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	$49.68	7.628%	$53.4696	$53.47	$53.45	$53.50
Purchase #2	$79.67	13.404%	$90.349	$90.35	$90.35	$90.30
Purchase #3	$177.96	5.264%	$187.3278	$187.33	$187.35	$187.30
Purchase #4	$187.48	11.805%	$209.612	$209.61	$209.60	$209.60
Purchase #5	$217.72	13.123%	$246.2914	$246.29	$246.30	$246.30
Purchase #6	$214.85	3.694%	$222.7866	$222.79	$222.80	$222.80
Purchase #7	$208.45	4.678%	$218.2013	$218.20	$218.20	$218.20
7 purchase totals =	$1,135.81		$1,228.0377	$1,228.04	$1,228.05	$1,228.00