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	$238.38	4.386%	$248.8353	$248.84	$248.85	$248.80
Purchase #2	$130.59	13.348%	$148.0212	$148.02	$148.00	$148.00
Purchase #3	$67.95	9.799%	$74.6084	$74.61	$74.60	$74.60
Purchase #4	$8.89	12.644%	$10.0141	$10.01	$10.00	$10.00
Purchase #5	$208.60	11.580%	$232.7559	$232.76	$232.75	$232.80
Purchase #6	$99.62	12.301%	$111.8743	$111.87	$111.85	$111.90
Purchase #7	$220.90	3.155%	$227.8694	$227.87	$227.85	$227.90
7 purchase totals =	$974.93		$1,053.9786	$1,053.98	$1,053.90	$1,054.00