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	$98.92	9.635%	$108.4509	$108.45	$108.45	$108.50
Purchase #2	$153.66	9.181%	$167.7675	$167.77	$167.75	$167.80
Purchase #3	$13.85	11.352%	$15.4223	$15.42	$15.40	$15.40
Purchase #4	$120.89	9.270%	$132.0965	$132.10	$132.10	$132.10
Purchase #5	$56.73	4.583%	$59.3299	$59.33	$59.35	$59.30
Purchase #6	$135.29	9.689%	$148.3982	$148.40	$148.40	$148.40
Purchase #7	$86.52	9.694%	$94.9072	$94.91	$94.90	$94.90
7 purchase totals =	$665.86		$726.3725	$726.38	$726.35	$726.40