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	$133.34	12.598%	$150.1382	$150.14	$150.15	$150.10
Purchase #2	$132.44	6.556%	$141.1228	$141.12	$141.10	$141.10
Purchase #3	$7.43	6.197%	$7.8904	$7.89	$7.90	$7.90
Purchase #4	$106.95	4.754%	$112.0344	$112.03	$112.05	$112.00
Purchase #5	$229.40	11.404%	$255.5608	$255.56	$255.55	$255.60
Purchase #6	$9.66	4.172%	$10.063	$10.06	$10.05	$10.10
Purchase #7	$169.55	4.189%	$176.6524	$176.65	$176.65	$176.70
7 purchase totals =	$788.77		$853.4620	$853.45	$853.45	$853.50