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	$148.70	10.870%	$164.8637	$164.86	$164.85	$164.90
Purchase #2	$99.39	4.804%	$104.1647	$104.16	$104.15	$104.20
Purchase #3	$44.34	9.663%	$48.6246	$48.62	$48.60	$48.60
Purchase #4	$197.82	12.127%	$221.8096	$221.81	$221.80	$221.80
Purchase #5	$205.62	3.374%	$212.5576	$212.56	$212.55	$212.60
Purchase #6	$115.43	12.288%	$129.614	$129.61	$129.60	$129.60
Purchase #7	$213.52	13.206%	$241.7175	$241.72	$241.70	$241.70
7 purchase totals =	$1,024.82		$1,123.3517	$1,123.34	$1,123.25	$1,123.40