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	$103.72	8.189%	$112.2136	$112.21	$112.20	$112.20
Purchase #2	$228.32	8.174%	$246.9829	$246.98	$247.00	$247.00
Purchase #3	$187.60	5.226%	$197.404	$197.40	$197.40	$197.40
Purchase #4	$56.77	4.243%	$59.1788	$59.18	$59.20	$59.20
Purchase #5	$47.89	13.484%	$54.3475	$54.35	$54.35	$54.30
Purchase #6	$241.97	5.594%	$255.5058	$255.51	$255.50	$255.50
Purchase #7	$209.73	9.614%	$229.8934	$229.89	$229.90	$229.90
7 purchase totals =	$1,076.00		$1,155.5260	$1,155.52	$1,155.55	$1,155.50