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	$211.43	9.592%	$231.7104	$231.71	$231.70	$231.70
Purchase #2	$176.37	13.842%	$200.7831	$200.78	$200.80	$200.80
Purchase #3	$187.73	4.599%	$196.3637	$196.36	$196.35	$196.40
Purchase #4	$61.34	3.354%	$63.3973	$63.40	$63.40	$63.40
Purchase #5	$229.35	13.408%	$260.1012	$260.10	$260.10	$260.10
Purchase #6	$192.27	12.611%	$216.5172	$216.52	$216.50	$216.50
Purchase #7	$67.34	13.788%	$76.6248	$76.62	$76.60	$76.60
7 purchase totals =	$1,125.83		$1,245.4977	$1,245.49	$1,245.45	$1,245.50