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	$118.81	13.432%	$134.7686	$134.77	$134.75	$134.80
Purchase #2	$127.49	7.854%	$137.5031	$137.50	$137.50	$137.50
Purchase #3	$203.40	5.452%	$214.4894	$214.49	$214.50	$214.50
Purchase #4	$59.94	4.797%	$62.8153	$62.82	$62.80	$62.80
Purchase #5	$169.36	4.814%	$177.513	$177.51	$177.50	$177.50
Purchase #6	$183.25	12.280%	$205.7531	$205.75	$205.75	$205.80
Purchase #7	$80.37	12.141%	$90.1277	$90.13	$90.15	$90.10
7 purchase totals =	$942.62		$1,022.9702	$1,022.97	$1,022.95	$1,023.00