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	$96.43	8.210%	$104.3469	$104.35	$104.35	$104.30
Purchase #2	$100.59	3.847%	$104.4597	$104.46	$104.45	$104.50
Purchase #3	$130.61	4.571%	$136.5802	$136.58	$136.60	$136.60
Purchase #4	$137.27	5.190%	$144.3943	$144.39	$144.40	$144.40
Purchase #5	$229.93	11.160%	$255.5902	$255.59	$255.60	$255.60
Purchase #6	$148.66	8.269%	$160.9527	$160.95	$160.95	$161.00
Purchase #7	$179.86	11.455%	$200.463	$200.46	$200.45	$200.50
7 purchase totals =	$1,023.35		$1,106.7870	$1,106.78	$1,106.80	$1,106.90