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	$43.40	6.349%	$46.1555	$46.16	$46.15	$46.20
Purchase #2	$84.73	5.279%	$89.2029	$89.20	$89.20	$89.20
Purchase #3	$241.58	4.565%	$252.6081	$252.61	$252.60	$252.60
Purchase #4	$112.97	9.693%	$123.9202	$123.92	$123.90	$123.90
Purchase #5	$159.90	13.322%	$181.2019	$181.20	$181.20	$181.20
Purchase #6	$106.35	5.182%	$111.8611	$111.86	$111.85	$111.90
Purchase #7	$89.43	10.539%	$98.855	$98.86	$98.85	$98.90
7 purchase totals =	$838.36		$903.8047	$903.81	$903.75	$903.90