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	$12.79	9.286%	$13.9777	$13.98	$14.00	$14.00
Purchase #2	$62.55	13.287%	$70.861	$70.86	$70.85	$70.90
Purchase #3	$103.53	7.662%	$111.4625	$111.46	$111.45	$111.50
Purchase #4	$137.52	9.160%	$150.1168	$150.12	$150.10	$150.10
Purchase #5	$245.70	8.221%	$265.899	$265.90	$265.90	$265.90
Purchase #6	$148.76	7.842%	$160.4258	$160.43	$160.45	$160.40
Purchase #7	$56.48	12.697%	$63.6513	$63.65	$63.65	$63.70
7 purchase totals =	$767.33		$836.3941	$836.40	$836.40	$836.50