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	$174.81	11.856%	$195.5355	$195.54	$195.55	$195.50
Purchase #2	$54.90	3.267%	$56.6936	$56.69	$56.70	$56.70
Purchase #3	$91.45	5.850%	$96.7998	$96.80	$96.80	$96.80
Purchase #4	$172.25	4.818%	$180.549	$180.55	$180.55	$180.50
Purchase #5	$236.57	9.395%	$258.7958	$258.80	$258.80	$258.80
Purchase #6	$109.91	7.168%	$117.7883	$117.79	$117.80	$117.80
Purchase #7	$111.80	13.671%	$127.0842	$127.08	$127.10	$127.10
7 purchase totals =	$951.69		$1,033.2462	$1,033.25	$1,033.30	$1,033.20