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	$217.56	5.673%	$229.9022	$229.90	$229.90	$229.90
Purchase #2	$54.37	3.298%	$56.1631	$56.16	$56.15	$56.20
Purchase #3	$239.56	5.144%	$251.883	$251.88	$251.90	$251.90
Purchase #4	$75.59	3.256%	$78.0512	$78.05	$78.05	$78.10
Purchase #5	$18.60	5.194%	$19.5661	$19.57	$19.55	$19.60
Purchase #6	$214.90	3.555%	$222.5397	$222.54	$222.55	$222.50
Purchase #7	$180.83	10.599%	$199.9962	$200.00	$200.00	$200.00
7 purchase totals =	$1,001.41		$1,058.1015	$1,058.10	$1,058.10	$1,058.20