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	$172.98	13.857%	$196.9498	$196.95	$196.95	$196.90
Purchase #2	$163.75	3.785%	$169.9479	$169.95	$169.95	$169.90
Purchase #3	$148.35	11.613%	$165.5779	$165.58	$165.60	$165.60
Purchase #4	$147.92	11.356%	$164.7178	$164.72	$164.70	$164.70
Purchase #5	$98.49	12.598%	$110.8978	$110.90	$110.90	$110.90
Purchase #6	$222.81	8.613%	$242.0006	$242.00	$242.00	$242.00
Purchase #7	$16.87	9.228%	$18.4268	$18.43	$18.45	$18.40
7 purchase totals =	$971.17		$1,068.5186	$1,068.53	$1,068.55	$1,068.40