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	$196.98	4.559%	$205.9603	$205.96	$205.95	$206.00
Purchase #2	$103.64	11.849%	$115.9203	$115.92	$115.90	$115.90
Purchase #3	$103.30	10.446%	$114.0907	$114.09	$114.10	$114.10
Purchase #4	$151.32	10.797%	$167.658	$167.66	$167.65	$167.70
Purchase #5	$229.95	11.121%	$255.5227	$255.52	$255.50	$255.50
Purchase #6	$39.37	11.280%	$43.8109	$43.81	$43.80	$43.80
Purchase #7	$191.86	12.817%	$216.4507	$216.45	$216.45	$216.50
7 purchase totals =	$1,016.42		$1,119.4136	$1,119.41	$1,119.35	$1,119.50