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	$195.81	9.750%	$214.9015	$214.90	$214.90	$214.90
Purchase #2	$82.63	8.421%	$89.5883	$89.59	$89.60	$89.60
Purchase #3	$39.68	3.471%	$41.0573	$41.06	$41.05	$41.10
Purchase #4	$133.33	3.843%	$138.4539	$138.45	$138.45	$138.50
Purchase #5	$222.78	10.254%	$245.6239	$245.62	$245.60	$245.60
Purchase #6	$122.39	7.321%	$131.3502	$131.35	$131.35	$131.40
Purchase #7	$195.40	6.476%	$208.0541	$208.05	$208.05	$208.10
7 purchase totals =	$992.02		$1,069.0292	$1,069.02	$1,069.00	$1,069.20