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	$122.87	4.132%	$127.947	$127.95	$127.95	$127.90
Purchase #2	$170.30	6.577%	$181.5006	$181.50	$181.50	$181.50
Purchase #3	$28.78	7.341%	$30.8927	$30.89	$30.90	$30.90
Purchase #4	$175.44	3.554%	$181.6751	$181.68	$181.70	$181.70
Purchase #5	$31.41	11.760%	$35.1038	$35.10	$35.10	$35.10
Purchase #6	$225.50	8.383%	$244.4037	$244.40	$244.40	$244.40
Purchase #7	$151.51	8.259%	$164.0232	$164.02	$164.00	$164.00
7 purchase totals =	$905.81		$965.5461	$965.54	$965.55	$965.50