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	$141.69	4.139%	$147.5545	$147.55	$147.55	$147.60
Purchase #2	$49.52	9.132%	$54.0422	$54.04	$54.05	$54.00
Purchase #3	$56.31	6.161%	$59.7793	$59.78	$59.80	$59.80
Purchase #4	$168.33	6.389%	$179.0846	$179.08	$179.10	$179.10
Purchase #5	$108.87	10.523%	$120.3264	$120.33	$120.35	$120.30
Purchase #6	$66.96	10.247%	$73.8214	$73.82	$73.80	$73.80
Purchase #7	$102.49	9.247%	$111.9673	$111.97	$111.95	$112.00
7 purchase totals =	$694.17		$746.5757	$746.57	$746.60	$746.60