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	$104.28	4.295%	$108.7588	$108.76	$108.75	$108.80
Purchase #2	$73.35	7.527%	$78.8711	$78.87	$78.85	$78.90
Purchase #3	$81.83	13.531%	$92.9024	$92.90	$92.90	$92.90
Purchase #4	$151.95	5.688%	$160.5929	$160.59	$160.60	$160.60
Purchase #5	$234.77	11.149%	$260.9445	$260.94	$260.95	$260.90
Purchase #6	$123.43	7.262%	$132.3935	$132.39	$132.40	$132.40
Purchase #7	$168.93	13.618%	$191.9349	$191.93	$191.95	$191.90
7 purchase totals =	$938.54		$1,026.3981	$1,026.38	$1,026.40	$1,026.40