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	$190.88	7.415%	$205.0338	$205.03	$205.05	$205.00
Purchase #2	$173.94	12.127%	$195.0337	$195.03	$195.05	$195.00
Purchase #3	$181.47	3.335%	$187.522	$187.52	$187.50	$187.50
Purchase #4	$208.33	3.460%	$215.5382	$215.54	$215.55	$215.50
Purchase #5	$247.62	3.552%	$256.4155	$256.42	$256.40	$256.40
Purchase #6	$159.72	3.574%	$165.4284	$165.43	$165.45	$165.40
Purchase #7	$43.71	7.203%	$46.8584	$46.86	$46.85	$46.90
7 purchase totals =	$1,205.67		$1,271.8300	$1,271.83	$1,271.85	$1,271.70