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	$59.50	6.433%	$63.3276	$63.33	$63.35	$63.30
Purchase #2	$67.57	4.821%	$70.8275	$70.83	$70.85	$70.80
Purchase #3	$94.57	4.596%	$98.9164	$98.92	$98.90	$98.90
Purchase #4	$154.71	3.429%	$160.015	$160.02	$160.00	$160.00
Purchase #5	$243.37	4.497%	$254.3143	$254.31	$254.30	$254.30
Purchase #6	$151.83	13.295%	$172.0158	$172.02	$172.00	$172.00
Purchase #7	$192.48	12.402%	$216.3514	$216.35	$216.35	$216.40
7 purchase totals =	$964.03		$1,035.7680	$1,035.78	$1,035.75	$1,035.70