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	$55.88	7.280%	$59.9481	$59.95	$59.95	$59.90
Purchase #2	$200.75	9.234%	$219.2873	$219.29	$219.30	$219.30
Purchase #3	$49.54	5.709%	$52.3682	$52.37	$52.35	$52.40
Purchase #4	$119.30	5.189%	$125.4905	$125.49	$125.50	$125.50
Purchase #5	$249.58	13.802%	$284.027	$284.03	$284.05	$284.00
Purchase #6	$142.84	13.608%	$162.2777	$162.28	$162.30	$162.30
Purchase #7	$224.60	10.222%	$247.5586	$247.56	$247.55	$247.60
7 purchase totals =	$1,042.49		$1,150.9574	$1,150.97	$1,151.00	$1,151.00