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	$200.76	8.719%	$218.2643	$218.26	$218.25	$218.30
Purchase #2	$248.35	13.688%	$282.3441	$282.34	$282.35	$282.30
Purchase #3	$103.31	5.337%	$108.8237	$108.82	$108.80	$108.80
Purchase #4	$19.61	10.627%	$21.694	$21.69	$21.70	$21.70
Purchase #5	$65.44	10.461%	$72.2857	$72.29	$72.30	$72.30
Purchase #6	$145.36	5.591%	$153.4871	$153.49	$153.50	$153.50
Purchase #7	$225.78	10.564%	$249.6314	$249.63	$249.65	$249.60
7 purchase totals =	$1,008.61		$1,106.5303	$1,106.52	$1,106.55	$1,106.50