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	$116.68	7.392%	$125.305	$125.31	$125.30	$125.30
Purchase #2	$19.98	11.439%	$22.2655	$22.27	$22.25	$22.30
Purchase #3	$205.74	13.477%	$233.4676	$233.47	$233.45	$233.50
Purchase #4	$142.54	11.461%	$158.8765	$158.88	$158.90	$158.90
Purchase #5	$72.97	12.818%	$82.3233	$82.32	$82.30	$82.30
Purchase #6	$239.33	9.626%	$262.3679	$262.37	$262.35	$262.40
Purchase #7	$88.90	11.394%	$99.0293	$99.03	$99.05	$99.00
7 purchase totals =	$886.14		$983.6351	$983.65	$983.60	$983.70