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	$111.45	4.385%	$116.3371	$116.34	$116.35	$116.30
Purchase #2	$154.68	3.487%	$160.0737	$160.07	$160.05	$160.10
Purchase #3	$53.87	3.322%	$55.6596	$55.66	$55.65	$55.70
Purchase #4	$200.72	3.794%	$208.3353	$208.34	$208.35	$208.30
Purchase #5	$36.43	12.573%	$41.0103	$41.01	$41.00	$41.00
Purchase #6	$179.38	3.460%	$185.5865	$185.59	$185.60	$185.60
Purchase #7	$230.51	7.493%	$247.7821	$247.78	$247.80	$247.80
7 purchase totals =	$967.04		$1,014.7846	$1,014.79	$1,014.80	$1,014.80