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	$198.70	10.655%	$219.8715	$219.87	$219.85	$219.90
Purchase #2	$158.89	9.541%	$174.0497	$174.05	$174.05	$174.00
Purchase #3	$161.53	12.655%	$181.9716	$181.97	$181.95	$182.00
Purchase #4	$41.45	12.127%	$46.4766	$46.48	$46.50	$46.50
Purchase #5	$130.40	10.292%	$143.8208	$143.82	$143.80	$143.80
Purchase #6	$155.95	5.476%	$164.4898	$164.49	$164.50	$164.50
Purchase #7	$151.77	11.721%	$169.559	$169.56	$169.55	$169.60
7 purchase totals =	$998.69		$1,100.2390	$1,100.24	$1,100.20	$1,100.30