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	$198.81	10.347%	$219.3809	$219.38	$219.40	$219.40
Purchase #2	$239.80	5.577%	$253.1736	$253.17	$253.15	$253.20
Purchase #3	$141.82	7.426%	$152.3516	$152.35	$152.35	$152.40
Purchase #4	$41.49	3.460%	$42.9256	$42.93	$42.95	$42.90
Purchase #5	$215.93	10.628%	$238.879	$238.88	$238.90	$238.90
Purchase #6	$193.51	6.123%	$205.3586	$205.36	$205.35	$205.40
Purchase #7	$62.43	7.592%	$67.1697	$67.17	$67.15	$67.20
7 purchase totals =	$1,093.79		$1,179.2390	$1,179.24	$1,179.25	$1,179.40