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	$229.48	8.477%	$248.933	$248.93	$248.95	$248.90
Purchase #2	$29.91	5.798%	$31.6442	$31.64	$31.65	$31.60
Purchase #3	$172.75	6.383%	$183.7766	$183.78	$183.80	$183.80
Purchase #4	$96.94	8.362%	$105.0461	$105.05	$105.05	$105.00
Purchase #5	$143.66	6.406%	$152.8629	$152.86	$152.85	$152.90
Purchase #6	$165.43	12.756%	$186.5323	$186.53	$186.55	$186.50
Purchase #7	$101.81	6.113%	$108.0336	$108.03	$108.05	$108.00
7 purchase totals =	$939.98		$1,016.8287	$1,016.82	$1,016.90	$1,016.70