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	$118.76	7.693%	$127.8962	$127.90	$127.90	$127.90
Purchase #2	$202.57	12.306%	$227.4983	$227.50	$227.50	$227.50
Purchase #3	$120.59	6.138%	$127.9918	$127.99	$128.00	$128.00
Purchase #4	$166.38	3.739%	$172.6009	$172.60	$172.60	$172.60
Purchase #5	$217.56	12.326%	$244.3764	$244.38	$244.40	$244.40
Purchase #6	$231.30	6.176%	$245.5851	$245.59	$245.60	$245.60
Purchase #7	$87.78	12.389%	$98.6551	$98.66	$98.65	$98.70
7 purchase totals =	$1,144.94		$1,244.6038	$1,244.62	$1,244.65	$1,244.70