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	$143.47	5.377%	$151.1844	$151.18	$151.20	$151.20
Purchase #2	$225.26	10.808%	$249.6061	$249.61	$249.60	$249.60
Purchase #3	$68.45	5.765%	$72.3961	$72.40	$72.40	$72.40
Purchase #4	$49.43	7.644%	$53.2084	$53.21	$53.20	$53.20
Purchase #5	$131.51	8.630%	$142.8593	$142.86	$142.85	$142.90
Purchase #6	$89.74	5.739%	$94.8902	$94.89	$94.90	$94.90
Purchase #7	$90.55	8.633%	$98.3672	$98.37	$98.35	$98.40
7 purchase totals =	$798.41		$862.5117	$862.52	$862.50	$862.60