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	$116.88	7.814%	$126.013	$126.01	$126.00	$126.00
Purchase #2	$237.81	7.241%	$255.0298	$255.03	$255.05	$255.00
Purchase #3	$45.69	6.470%	$48.6461	$48.65	$48.65	$48.60
Purchase #4	$142.62	5.390%	$150.3072	$150.31	$150.30	$150.30
Purchase #5	$193.43	9.315%	$211.448	$211.45	$211.45	$211.40
Purchase #6	$75.68	3.553%	$78.3689	$78.37	$78.35	$78.40
Purchase #7	$104.36	11.311%	$116.1642	$116.16	$116.15	$116.20
7 purchase totals =	$916.47		$985.9772	$985.98	$985.95	$985.90