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	$152.70	7.548%	$164.2258	$164.23	$164.25	$164.20
Purchase #2	$194.75	13.713%	$221.4561	$221.46	$221.45	$221.50
Purchase #3	$33.52	4.217%	$34.9335	$34.93	$34.95	$34.90
Purchase #4	$134.34	4.182%	$139.9581	$139.96	$139.95	$140.00
Purchase #5	$142.27	6.338%	$151.2871	$151.29	$151.30	$151.30
Purchase #6	$94.44	5.390%	$99.5303	$99.53	$99.55	$99.50
Purchase #7	$208.50	10.349%	$230.0777	$230.08	$230.10	$230.10
7 purchase totals =	$960.52		$1,041.4686	$1,041.48	$1,041.55	$1,041.50