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	$192.62	6.599%	$205.331	$205.33	$205.35	$205.30
Purchase #2	$194.53	3.710%	$201.7471	$201.75	$201.75	$201.70
Purchase #3	$219.87	11.861%	$245.9488	$245.95	$245.95	$245.90
Purchase #4	$38.89	10.105%	$42.8198	$42.82	$42.80	$42.80
Purchase #5	$72.96	5.365%	$76.8743	$76.87	$76.85	$76.90
Purchase #6	$82.48	8.430%	$89.4331	$89.43	$89.45	$89.40
Purchase #7	$152.39	4.257%	$158.8772	$158.88	$158.90	$158.90
7 purchase totals =	$953.74		$1,021.0313	$1,021.03	$1,021.05	$1,020.90