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	$107.56	5.765%	$113.7608	$113.76	$113.75	$113.80
Purchase #2	$166.57	10.751%	$184.4779	$184.48	$184.50	$184.50
Purchase #3	$157.33	3.388%	$162.6603	$162.66	$162.65	$162.70
Purchase #4	$67.72	5.421%	$71.3911	$71.39	$71.40	$71.40
Purchase #5	$10.83	9.788%	$11.89	$11.89	$11.90	$11.90
Purchase #6	$118.34	10.583%	$130.8639	$130.86	$130.85	$130.90
Purchase #7	$81.32	5.756%	$86.0008	$86.00	$86.00	$86.00
7 purchase totals =	$709.67		$761.0448	$761.04	$761.05	$761.20