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	$219.65	8.789%	$238.955	$238.96	$238.95	$239.00
Purchase #2	$33.47	9.303%	$36.5837	$36.58	$36.60	$36.60
Purchase #3	$230.42	5.224%	$242.4571	$242.46	$242.45	$242.50
Purchase #4	$71.35	10.621%	$78.9281	$78.93	$78.95	$78.90
Purchase #5	$190.65	10.420%	$210.5157	$210.52	$210.50	$210.50
Purchase #6	$161.77	10.500%	$178.7559	$178.76	$178.75	$178.80
Purchase #7	$69.84	3.591%	$72.348	$72.35	$72.35	$72.30
7 purchase totals =	$977.15		$1,058.5435	$1,058.56	$1,058.55	$1,058.60