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	$245.54	8.253%	$265.8044	$265.80	$265.80	$265.80
Purchase #2	$246.25	6.204%	$261.5274	$261.53	$261.55	$261.50
Purchase #3	$94.72	3.760%	$98.2815	$98.28	$98.30	$98.30
Purchase #4	$82.70	9.808%	$90.8112	$90.81	$90.80	$90.80
Purchase #5	$142.93	7.345%	$153.4282	$153.43	$153.45	$153.40
Purchase #6	$32.93	9.514%	$36.063	$36.06	$36.05	$36.10
Purchase #7	$114.46	4.608%	$119.7343	$119.73	$119.75	$119.70
7 purchase totals =	$959.53		$1,025.6500	$1,025.64	$1,025.70	$1,025.60