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	$224.89	3.607%	$233.0018	$233.00	$233.00	$233.00
Purchase #2	$81.97	10.788%	$90.8129	$90.81	$90.80	$90.80
Purchase #3	$74.34	5.210%	$78.2131	$78.21	$78.20	$78.20
Purchase #4	$14.84	11.724%	$16.5798	$16.58	$16.60	$16.60
Purchase #5	$70.75	8.280%	$76.6081	$76.61	$76.60	$76.60
Purchase #6	$53.59	11.181%	$59.5819	$59.58	$59.60	$59.60
Purchase #7	$182.81	8.439%	$198.2373	$198.24	$198.25	$198.20
7 purchase totals =	$703.19		$753.0349	$753.03	$753.05	$753.00