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	$191.75	7.660%	$206.4381	$206.44	$206.45	$206.40
Purchase #2	$201.38	7.187%	$215.8532	$215.85	$215.85	$215.90
Purchase #3	$126.45	6.601%	$134.797	$134.80	$134.80	$134.80
Purchase #4	$88.93	13.451%	$100.892	$100.89	$100.90	$100.90
Purchase #5	$158.50	4.367%	$165.4217	$165.42	$165.40	$165.40
Purchase #6	$186.57	11.501%	$208.0274	$208.03	$208.05	$208.00
Purchase #7	$10.49	4.640%	$10.9767	$10.98	$11.00	$11.00
7 purchase totals =	$964.07		$1,042.4061	$1,042.41	$1,042.45	$1,042.40