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	$72.50	5.329%	$76.3635	$76.36	$76.35	$76.40
Purchase #2	$13.92	6.458%	$14.819	$14.82	$14.80	$14.80
Purchase #3	$57.41	8.204%	$62.1199	$62.12	$62.10	$62.10
Purchase #4	$104.27	6.456%	$111.0017	$111.00	$111.00	$111.00
Purchase #5	$10.43	3.375%	$10.782	$10.78	$10.80	$10.80
Purchase #6	$48.33	8.707%	$52.5381	$52.54	$52.55	$52.50
Purchase #7	$48.97	13.524%	$55.5927	$55.59	$55.60	$55.60
7 purchase totals =	$355.83		$383.2169	$383.21	$383.20	$383.20