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	$186.86	4.274%	$194.8464	$194.85	$194.85	$194.80
Purchase #2	$100.27	4.442%	$104.724	$104.72	$104.70	$104.70
Purchase #3	$205.35	5.360%	$216.3568	$216.36	$216.35	$216.40
Purchase #4	$129.72	11.470%	$144.5989	$144.60	$144.60	$144.60
Purchase #5	$70.61	4.532%	$73.81	$73.81	$73.80	$73.80
Purchase #6	$101.82	3.156%	$105.0334	$105.03	$105.05	$105.00
Purchase #7	$162.40	7.310%	$174.2714	$174.27	$174.25	$174.30
7 purchase totals =	$957.03		$1,013.6409	$1,013.64	$1,013.60	$1,013.60