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	$195.67	7.705%	$210.7464	$210.75	$210.75	$210.70
Purchase #2	$68.48	6.490%	$72.9244	$72.92	$72.90	$72.90
Purchase #3	$109.95	12.702%	$123.9158	$123.92	$123.90	$123.90
Purchase #4	$187.38	11.630%	$209.1723	$209.17	$209.15	$209.20
Purchase #5	$10.28	11.717%	$11.4845	$11.48	$11.50	$11.50
Purchase #6	$223.95	13.791%	$254.8349	$254.83	$254.85	$254.80
Purchase #7	$123.96	13.407%	$140.5793	$140.58	$140.60	$140.60
7 purchase totals =	$919.67		$1,023.6576	$1,023.65	$1,023.65	$1,023.60