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	$151.50	4.724%	$158.6569	$158.66	$158.65	$158.70
Purchase #2	$87.40	13.796%	$99.4577	$99.46	$99.45	$99.50
Purchase #3	$36.45	9.336%	$39.853	$39.85	$39.85	$39.90
Purchase #4	$65.58	9.137%	$71.572	$71.57	$71.55	$71.60
Purchase #5	$220.75	3.269%	$227.9663	$227.97	$227.95	$228.00
Purchase #6	$176.31	11.373%	$196.3617	$196.36	$196.35	$196.40
Purchase #7	$216.70	12.867%	$244.5828	$244.58	$244.60	$244.60
7 purchase totals =	$954.69		$1,038.4504	$1,038.45	$1,038.40	$1,038.70