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	$180.53	8.622%	$196.0953	$196.10	$196.10	$196.10
Purchase #2	$126.72	3.778%	$131.5075	$131.51	$131.50	$131.50
Purchase #3	$215.35	5.323%	$226.8131	$226.81	$226.80	$226.80
Purchase #4	$10.87	6.116%	$11.5348	$11.53	$11.55	$11.50
Purchase #5	$174.69	8.601%	$189.7151	$189.72	$189.70	$189.70
Purchase #6	$209.78	4.515%	$219.2516	$219.25	$219.25	$219.30
Purchase #7	$143.40	8.530%	$155.632	$155.63	$155.65	$155.60
7 purchase totals =	$1,061.34		$1,130.5494	$1,130.55	$1,130.55	$1,130.50