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	$171.43	13.859%	$195.1885	$195.19	$195.20	$195.20
Purchase #2	$190.46	13.147%	$215.4998	$215.50	$215.50	$215.50
Purchase #3	$132.89	8.791%	$144.5724	$144.57	$144.55	$144.60
Purchase #4	$168.30	11.485%	$187.6293	$187.63	$187.65	$187.60
Purchase #5	$36.56	7.113%	$39.1605	$39.16	$39.15	$39.20
Purchase #6	$178.25	10.326%	$196.6561	$196.66	$196.65	$196.70
Purchase #7	$58.80	12.129%	$65.9319	$65.93	$65.95	$65.90
7 purchase totals =	$936.69		$1,044.6385	$1,044.64	$1,044.65	$1,044.70