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	$153.83	4.553%	$160.8339	$160.83	$160.85	$160.80
Purchase #2	$66.99	8.870%	$72.932	$72.93	$72.95	$72.90
Purchase #3	$174.67	11.368%	$194.5265	$194.53	$194.55	$194.50
Purchase #4	$28.53	12.210%	$32.0135	$32.01	$32.00	$32.00
Purchase #5	$39.87	8.836%	$43.3929	$43.39	$43.40	$43.40
Purchase #6	$71.89	10.402%	$79.368	$79.37	$79.35	$79.40
Purchase #7	$197.38	3.624%	$204.5331	$204.53	$204.55	$204.50
7 purchase totals =	$733.16		$787.5999	$787.59	$787.65	$787.50