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	$192.42	10.729%	$213.0647	$213.06	$213.05	$213.10
Purchase #2	$235.59	4.825%	$246.9572	$246.96	$246.95	$247.00
Purchase #3	$164.31	11.291%	$182.8622	$182.86	$182.85	$182.90
Purchase #4	$92.51	10.206%	$101.9516	$101.95	$101.95	$102.00
Purchase #5	$67.33	7.672%	$72.4956	$72.50	$72.50	$72.50
Purchase #6	$94.61	11.748%	$105.7248	$105.72	$105.70	$105.70
Purchase #7	$150.64	5.529%	$158.9689	$158.97	$158.95	$159.00
7 purchase totals =	$997.41		$1,082.0250	$1,082.02	$1,081.95	$1,082.20