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	$195.78	4.766%	$205.1109	$205.11	$205.10	$205.10
Purchase #2	$106.91	11.299%	$118.9898	$118.99	$119.00	$119.00
Purchase #3	$122.26	8.679%	$132.8709	$132.87	$132.85	$132.90
Purchase #4	$195.94	13.823%	$223.0248	$223.02	$223.00	$223.00
Purchase #5	$29.86	11.544%	$33.307	$33.31	$33.30	$33.30
Purchase #6	$35.45	12.424%	$39.8543	$39.85	$39.85	$39.90
Purchase #7	$63.72	13.426%	$72.275	$72.28	$72.30	$72.30
7 purchase totals =	$749.92		$825.4327	$825.43	$825.40	$825.50