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	$107.77	3.563%	$111.6098	$111.61	$111.60	$111.60
Purchase #2	$51.92	11.585%	$57.9349	$57.93	$57.95	$57.90
Purchase #3	$199.26	6.139%	$211.4926	$211.49	$211.50	$211.50
Purchase #4	$163.82	13.667%	$186.2093	$186.21	$186.20	$186.20
Purchase #5	$102.97	8.181%	$111.394	$111.39	$111.40	$111.40
Purchase #6	$226.59	12.106%	$254.021	$254.02	$254.00	$254.00
Purchase #7	$88.78	7.567%	$95.498	$95.50	$95.50	$95.50
7 purchase totals =	$941.11		$1,028.1596	$1,028.15	$1,028.15	$1,028.10