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	$87.61	9.175%	$95.6482	$95.65	$95.65	$95.60
Purchase #2	$139.36	8.543%	$151.2655	$151.27	$151.25	$151.30
Purchase #3	$55.60	7.805%	$59.9396	$59.94	$59.95	$59.90
Purchase #4	$93.59	3.504%	$96.8694	$96.87	$96.85	$96.90
Purchase #5	$229.71	8.480%	$249.1894	$249.19	$249.20	$249.20
Purchase #6	$32.25	7.814%	$34.77	$34.77	$34.75	$34.80
Purchase #7	$35.39	9.727%	$38.8324	$38.83	$38.85	$38.80
7 purchase totals =	$673.51		$726.5145	$726.52	$726.50	$726.50