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	$44.93	4.445%	$46.9271	$46.93	$46.95	$46.90
Purchase #2	$112.99	9.588%	$123.8235	$123.82	$123.80	$123.80
Purchase #3	$63.85	11.808%	$71.3894	$71.39	$71.40	$71.40
Purchase #4	$224.35	7.358%	$240.8577	$240.86	$240.85	$240.90
Purchase #5	$176.47	6.120%	$187.27	$187.27	$187.25	$187.30
Purchase #6	$51.88	7.162%	$55.5956	$55.60	$55.60	$55.60
Purchase #7	$72.97	7.359%	$78.3399	$78.34	$78.35	$78.30
7 purchase totals =	$747.44		$804.2032	$804.21	$804.20	$804.20