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	$246.63	7.434%	$264.9645	$264.96	$264.95	$265.00
Purchase #2	$98.82	6.686%	$105.4271	$105.43	$105.45	$105.40
Purchase #3	$70.43	11.235%	$78.3428	$78.34	$78.35	$78.30
Purchase #4	$48.97	7.616%	$52.6996	$52.70	$52.70	$52.70
Purchase #5	$40.61	11.813%	$45.4073	$45.41	$45.40	$45.40
Purchase #6	$31.41	4.219%	$32.7352	$32.74	$32.75	$32.70
Purchase #7	$112.84	7.757%	$121.593	$121.59	$121.60	$121.60
7 purchase totals =	$649.71		$701.1695	$701.17	$701.20	$701.10