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	$178.62	8.782%	$194.3064	$194.31	$194.30	$194.30
Purchase #2	$194.97	10.606%	$215.6485	$215.65	$215.65	$215.60
Purchase #3	$179.44	5.200%	$188.7709	$188.77	$188.75	$188.80
Purchase #4	$72.54	8.180%	$78.4738	$78.47	$78.45	$78.50
Purchase #5	$164.75	8.224%	$178.299	$178.30	$178.30	$178.30
Purchase #6	$136.40	13.461%	$154.7608	$154.76	$154.75	$154.80
Purchase #7	$51.69	4.138%	$53.8289	$53.83	$53.85	$53.80
7 purchase totals =	$978.41		$1,064.0883	$1,064.09	$1,064.05	$1,064.10