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	$83.78	13.365%	$94.9772	$94.98	$95.00	$95.00
Purchase #2	$47.40	3.397%	$49.0102	$49.01	$49.00	$49.00
Purchase #3	$189.60	3.498%	$196.2322	$196.23	$196.25	$196.20
Purchase #4	$73.91	6.663%	$78.8346	$78.83	$78.85	$78.80
Purchase #5	$203.86	11.833%	$227.9828	$227.98	$228.00	$228.00
Purchase #6	$184.74	7.821%	$199.1885	$199.19	$199.20	$199.20
Purchase #7	$208.47	5.234%	$219.3813	$219.38	$219.40	$219.40
7 purchase totals =	$991.76		$1,065.6068	$1,065.60	$1,065.70	$1,065.60