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	$163.77	13.488%	$185.8593	$185.86	$185.85	$185.90
Purchase #2	$144.73	7.729%	$155.9162	$155.92	$155.90	$155.90
Purchase #3	$52.99	13.758%	$60.2804	$60.28	$60.30	$60.30
Purchase #4	$88.60	13.653%	$100.6966	$100.70	$100.70	$100.70
Purchase #5	$220.78	5.466%	$232.8478	$232.85	$232.85	$232.80
Purchase #6	$138.94	8.437%	$150.6624	$150.66	$150.65	$150.70
Purchase #7	$189.61	10.534%	$209.5835	$209.58	$209.60	$209.60
7 purchase totals =	$999.42		$1,095.8462	$1,095.85	$1,095.85	$1,095.90