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	$208.32	4.834%	$218.3902	$218.39	$218.40	$218.40
Purchase #2	$53.98	13.287%	$61.1523	$61.15	$61.15	$61.20
Purchase #3	$104.30	11.451%	$116.2434	$116.24	$116.25	$116.20
Purchase #4	$222.29	12.429%	$249.9184	$249.92	$249.90	$249.90
Purchase #5	$92.60	10.689%	$102.498	$102.50	$102.50	$102.50
Purchase #6	$139.29	13.796%	$158.5064	$158.51	$158.50	$158.50
Purchase #7	$107.52	13.277%	$121.7954	$121.80	$121.80	$121.80
7 purchase totals =	$928.30		$1,028.5041	$1,028.51	$1,028.50	$1,028.50