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	$182.53	7.420%	$196.0737	$196.07	$196.05	$196.10
Purchase #2	$205.81	12.381%	$231.2913	$231.29	$231.30	$231.30
Purchase #3	$213.72	4.748%	$223.8674	$223.87	$223.85	$223.90
Purchase #4	$74.52	8.218%	$80.6441	$80.64	$80.65	$80.60
Purchase #5	$235.35	6.486%	$250.6148	$250.61	$250.60	$250.60
Purchase #6	$12.31	5.629%	$13.0029	$13.00	$13.00	$13.00
Purchase #7	$201.66	3.864%	$209.4521	$209.45	$209.45	$209.50
7 purchase totals =	$1,125.90		$1,204.9463	$1,204.93	$1,204.90	$1,205.00