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	$182.67	5.359%	$192.4593	$192.46	$192.45	$192.50
Purchase #2	$39.74	6.704%	$42.4042	$42.40	$42.40	$42.40
Purchase #3	$73.66	11.811%	$82.36	$82.36	$82.35	$82.40
Purchase #4	$202.70	10.483%	$223.949	$223.95	$223.95	$223.90
Purchase #5	$156.48	10.196%	$172.4347	$172.43	$172.45	$172.40
Purchase #6	$187.57	12.434%	$210.8925	$210.89	$210.90	$210.90
Purchase #7	$114.83	4.678%	$120.2017	$120.20	$120.20	$120.20
7 purchase totals =	$957.65		$1,044.7014	$1,044.69	$1,044.70	$1,044.70