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	$96.75	11.486%	$107.8627	$107.86	$107.85	$107.90
Purchase #2	$89.35	11.333%	$99.476	$99.48	$99.50	$99.50
Purchase #3	$192.50	8.417%	$208.7027	$208.70	$208.70	$208.70
Purchase #4	$146.68	3.378%	$151.6349	$151.63	$151.65	$151.60
Purchase #5	$205.78	11.773%	$230.0065	$230.01	$230.00	$230.00
Purchase #6	$93.49	5.221%	$98.3711	$98.37	$98.35	$98.40
Purchase #7	$72.88	13.275%	$82.5548	$82.55	$82.55	$82.60
7 purchase totals =	$897.43		$978.6087	$978.60	$978.60	$978.70