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	$173.69	9.209%	$189.6851	$189.69	$189.70	$189.70
Purchase #2	$172.89	8.185%	$187.041	$187.04	$187.05	$187.00
Purchase #3	$144.73	6.831%	$154.6165	$154.62	$154.60	$154.60
Purchase #4	$164.59	8.501%	$178.5818	$178.58	$178.60	$178.60
Purchase #5	$105.44	6.333%	$112.1175	$112.12	$112.10	$112.10
Purchase #6	$118.72	10.457%	$131.1346	$131.13	$131.15	$131.10
Purchase #7	$67.93	7.175%	$72.804	$72.80	$72.80	$72.80
7 purchase totals =	$947.99		$1,025.9805	$1,025.98	$1,026.00	$1,025.90