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	$196.52	11.493%	$219.106	$219.11	$219.10	$219.10
Purchase #2	$85.33	4.622%	$89.274	$89.27	$89.25	$89.30
Purchase #3	$74.74	13.299%	$84.6797	$84.68	$84.70	$84.70
Purchase #4	$121.78	4.337%	$127.0616	$127.06	$127.05	$127.10
Purchase #5	$83.51	9.584%	$91.5136	$91.51	$91.50	$91.50
Purchase #6	$32.60	6.702%	$34.7849	$34.78	$34.80	$34.80
Purchase #7	$105.44	12.835%	$118.9732	$118.97	$118.95	$119.00
7 purchase totals =	$699.92		$765.3930	$765.38	$765.35	$765.50