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	$193.62	11.187%	$215.2803	$215.28	$215.30	$215.30
Purchase #2	$103.95	5.242%	$109.3991	$109.40	$109.40	$109.40
Purchase #3	$244.86	4.287%	$255.3571	$255.36	$255.35	$255.40
Purchase #4	$224.70	13.158%	$254.266	$254.27	$254.25	$254.30
Purchase #5	$19.46	5.374%	$20.5058	$20.51	$20.50	$20.50
Purchase #6	$59.96	11.700%	$66.9753	$66.98	$67.00	$67.00
Purchase #7	$117.63	8.851%	$128.0414	$128.04	$128.05	$128.00
7 purchase totals =	$964.18		$1,049.8250	$1,049.84	$1,049.85	$1,049.90