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	$172.30	13.785%	$196.0516	$196.05	$196.05	$196.10
Purchase #2	$155.71	7.774%	$167.8149	$167.81	$167.80	$167.80
Purchase #3	$59.42	5.208%	$62.5146	$62.51	$62.50	$62.50
Purchase #4	$159.44	13.793%	$181.4316	$181.43	$181.45	$181.40
Purchase #5	$210.82	9.737%	$231.3475	$231.35	$231.35	$231.30
Purchase #6	$85.90	5.619%	$90.7267	$90.73	$90.75	$90.70
Purchase #7	$90.83	13.485%	$103.0784	$103.08	$103.10	$103.10
7 purchase totals =	$934.42		$1,032.9653	$1,032.96	$1,033.00	$1,032.90