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	$13.94	4.190%	$14.5241	$14.52	$14.50	$14.50
Purchase #2	$73.70	6.169%	$78.2466	$78.25	$78.25	$78.20
Purchase #3	$42.54	3.423%	$43.9961	$44.00	$44.00	$44.00
Purchase #4	$165.58	5.389%	$174.5031	$174.50	$174.50	$174.50
Purchase #5	$23.54	12.395%	$26.4578	$26.46	$26.45	$26.50
Purchase #6	$72.73	8.213%	$78.7033	$78.70	$78.70	$78.70
Purchase #7	$81.30	12.446%	$91.4186	$91.42	$91.40	$91.40
7 purchase totals =	$473.33		$507.8496	$507.85	$507.80	$507.80