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	$208.69	11.308%	$232.2887	$232.29	$232.30	$232.30
Purchase #2	$79.73	10.253%	$87.9047	$87.90	$87.90	$87.90
Purchase #3	$196.37	3.134%	$202.5242	$202.52	$202.50	$202.50
Purchase #4	$231.62	4.434%	$241.89	$241.89	$241.90	$241.90
Purchase #5	$31.32	3.249%	$32.3376	$32.34	$32.35	$32.30
Purchase #6	$12.52	5.594%	$13.2204	$13.22	$13.20	$13.20
Purchase #7	$187.46	11.841%	$209.6571	$209.66	$209.65	$209.70
7 purchase totals =	$947.71		$1,019.8227	$1,019.82	$1,019.80	$1,019.80