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	$143.59	7.156%	$153.8653	$153.87	$153.85	$153.90
Purchase #2	$217.37	5.294%	$228.8776	$228.88	$228.90	$228.90
Purchase #3	$112.74	12.655%	$127.0072	$127.01	$127.00	$127.00
Purchase #4	$133.92	5.766%	$141.6418	$141.64	$141.65	$141.60
Purchase #5	$200.32	12.417%	$225.1937	$225.19	$225.20	$225.20
Purchase #6	$59.48	6.419%	$63.298	$63.30	$63.30	$63.30
Purchase #7	$157.56	7.472%	$169.3329	$169.33	$169.35	$169.30
7 purchase totals =	$1,024.98		$1,109.2165	$1,109.22	$1,109.25	$1,109.20