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	$162.55	12.695%	$183.1857	$183.19	$183.20	$183.20
Purchase #2	$187.29	12.369%	$210.4559	$210.46	$210.45	$210.50
Purchase #3	$35.77	11.526%	$39.8929	$39.89	$39.90	$39.90
Purchase #4	$87.27	12.211%	$97.9265	$97.93	$97.95	$97.90
Purchase #5	$73.95	11.549%	$82.4905	$82.49	$82.50	$82.50
Purchase #6	$143.80	12.856%	$162.2869	$162.29	$162.30	$162.30
Purchase #7	$226.47	3.201%	$233.7193	$233.72	$233.70	$233.70
7 purchase totals =	$917.10		$1,009.9577	$1,009.97	$1,010.00	$1,010.00