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	$39.72	10.631%	$43.9426	$43.94	$43.95	$43.90
Purchase #2	$131.77	7.759%	$141.994	$141.99	$142.00	$142.00
Purchase #3	$45.84	10.191%	$50.5116	$50.51	$50.50	$50.50
Purchase #4	$175.50	12.225%	$196.9549	$196.95	$196.95	$197.00
Purchase #5	$151.52	13.449%	$171.8979	$171.90	$171.90	$171.90
Purchase #6	$208.33	8.212%	$225.4381	$225.44	$225.45	$225.40
Purchase #7	$190.46	4.152%	$198.3679	$198.37	$198.35	$198.40
7 purchase totals =	$943.14		$1,029.1070	$1,029.10	$1,029.10	$1,029.10