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	$41.52	10.461%	$45.8634	$45.86	$45.85	$45.90
Purchase #2	$134.55	13.477%	$152.6833	$152.68	$152.70	$152.70
Purchase #3	$234.59	7.246%	$251.5884	$251.59	$251.60	$251.60
Purchase #4	$206.94	9.428%	$226.4503	$226.45	$226.45	$226.50
Purchase #5	$142.93	13.668%	$162.4657	$162.47	$162.45	$162.50
Purchase #6	$146.54	9.243%	$160.0847	$160.08	$160.10	$160.10
Purchase #7	$116.38	6.768%	$124.2566	$124.26	$124.25	$124.30
7 purchase totals =	$1,023.45		$1,123.3924	$1,123.39	$1,123.40	$1,123.60