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	$214.38	6.272%	$227.8259	$227.83	$227.85	$227.80
Purchase #2	$63.51	4.130%	$66.133	$66.13	$66.15	$66.10
Purchase #3	$84.59	13.332%	$95.8675	$95.87	$95.85	$95.90
Purchase #4	$132.29	5.799%	$139.9615	$139.96	$139.95	$140.00
Purchase #5	$33.63	5.666%	$35.5355	$35.54	$35.55	$35.50
Purchase #6	$167.55	8.797%	$182.2894	$182.29	$182.30	$182.30
Purchase #7	$49.59	8.294%	$53.703	$53.70	$53.70	$53.70
7 purchase totals =	$745.54		$801.3158	$801.32	$801.35	$801.30