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	$46.61	4.373%	$48.6483	$48.65	$48.65	$48.60
Purchase #2	$146.48	11.116%	$162.7627	$162.76	$162.75	$162.80
Purchase #3	$155.33	13.213%	$175.8538	$175.85	$175.85	$175.90
Purchase #4	$154.76	5.294%	$162.953	$162.95	$162.95	$163.00
Purchase #5	$52.59	13.498%	$59.6886	$59.69	$59.70	$59.70
Purchase #6	$141.73	8.126%	$153.247	$153.25	$153.25	$153.20
Purchase #7	$221.97	11.863%	$248.3023	$248.30	$248.30	$248.30
7 purchase totals =	$919.47		$1,011.4557	$1,011.45	$1,011.45	$1,011.50