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	$105.43	6.279%	$112.0499	$112.05	$112.05	$112.00
Purchase #2	$27.63	10.439%	$30.5143	$30.51	$30.50	$30.50
Purchase #3	$101.62	6.786%	$108.5159	$108.52	$108.50	$108.50
Purchase #4	$98.31	11.617%	$109.7307	$109.73	$109.75	$109.70
Purchase #5	$172.79	3.771%	$179.3059	$179.31	$179.30	$179.30
Purchase #6	$205.26	4.749%	$215.0078	$215.01	$215.00	$215.00
Purchase #7	$238.30	3.845%	$247.4626	$247.46	$247.45	$247.50
7 purchase totals =	$949.34		$1,002.5871	$1,002.59	$1,002.55	$1,002.50