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	$48.50	10.553%	$53.6182	$53.62	$53.60	$53.60
Purchase #2	$216.43	10.264%	$238.6444	$238.64	$238.65	$238.60
Purchase #3	$94.87	7.163%	$101.6655	$101.67	$101.65	$101.70
Purchase #4	$150.49	10.448%	$166.2132	$166.21	$166.20	$166.20
Purchase #5	$206.70	10.260%	$227.9074	$227.91	$227.90	$227.90
Purchase #6	$105.76	5.181%	$111.2394	$111.24	$111.25	$111.20
Purchase #7	$152.37	11.750%	$170.2735	$170.27	$170.25	$170.30
7 purchase totals =	$975.12		$1,069.5616	$1,069.56	$1,069.50	$1,069.50