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	$89.35	6.396%	$95.0648	$95.06	$95.05	$95.10
Purchase #2	$148.95	6.213%	$158.2043	$158.20	$158.20	$158.20
Purchase #3	$187.26	6.765%	$199.9281	$199.93	$199.95	$199.90
Purchase #4	$120.92	6.161%	$128.3699	$128.37	$128.35	$128.40
Purchase #5	$189.59	8.158%	$205.0568	$205.06	$205.05	$205.10
Purchase #6	$116.68	9.273%	$127.4997	$127.50	$127.50	$127.50
Purchase #7	$205.43	13.686%	$233.5451	$233.55	$233.55	$233.50
7 purchase totals =	$1,058.18		$1,147.6687	$1,147.67	$1,147.65	$1,147.70