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	$68.91	8.350%	$74.664	$74.66	$74.65	$74.70
Purchase #2	$91.39	4.503%	$95.5053	$95.51	$95.50	$95.50
Purchase #3	$120.89	9.308%	$132.1424	$132.14	$132.15	$132.10
Purchase #4	$196.69	13.319%	$222.8871	$222.89	$222.90	$222.90
Purchase #5	$240.86	3.574%	$249.4683	$249.47	$249.45	$249.50
Purchase #6	$107.49	9.463%	$117.6618	$117.66	$117.65	$117.70
Purchase #7	$167.59	3.589%	$173.6048	$173.60	$173.60	$173.60
7 purchase totals =	$993.82		$1,065.9337	$1,065.93	$1,065.90	$1,066.00