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	$205.53	11.860%	$229.9059	$229.91	$229.90	$229.90
Purchase #2	$74.29	5.724%	$78.5424	$78.54	$78.55	$78.50
Purchase #3	$25.72	4.281%	$26.8211	$26.82	$26.80	$26.80
Purchase #4	$203.70	11.407%	$226.9361	$226.94	$226.95	$226.90
Purchase #5	$190.45	9.663%	$208.8532	$208.85	$208.85	$208.90
Purchase #6	$66.81	13.660%	$75.9362	$75.94	$75.95	$75.90
Purchase #7	$196.82	9.256%	$215.0377	$215.04	$215.05	$215.00
7 purchase totals =	$963.32		$1,062.0326	$1,062.04	$1,062.05	$1,061.90