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	$167.93	5.302%	$176.8336	$176.83	$176.85	$176.80
Purchase #2	$69.98	4.158%	$72.8898	$72.89	$72.90	$72.90
Purchase #3	$65.59	12.370%	$73.7035	$73.70	$73.70	$73.70
Purchase #4	$197.49	4.758%	$206.8866	$206.89	$206.90	$206.90
Purchase #5	$127.47	3.497%	$131.9276	$131.93	$131.95	$131.90
Purchase #6	$204.30	5.428%	$215.3894	$215.39	$215.40	$215.40
Purchase #7	$246.35	7.638%	$265.1662	$265.17	$265.15	$265.20
7 purchase totals =	$1,079.11		$1,142.7967	$1,142.80	$1,142.85	$1,142.80