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	$194.90	7.730%	$209.9658	$209.97	$209.95	$210.00
Purchase #2	$10.88	7.131%	$11.6559	$11.66	$11.65	$11.70
Purchase #3	$130.40	3.410%	$134.8466	$134.85	$134.85	$134.80
Purchase #4	$228.41	4.255%	$238.1288	$238.13	$238.15	$238.10
Purchase #5	$137.72	4.256%	$143.5814	$143.58	$143.60	$143.60
Purchase #6	$213.29	4.181%	$222.2077	$222.21	$222.20	$222.20
Purchase #7	$86.31	4.567%	$90.2518	$90.25	$90.25	$90.30
7 purchase totals =	$1,001.91		$1,050.6380	$1,050.65	$1,050.65	$1,050.70