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	$69.95	8.805%	$76.1091	$76.11	$76.10	$76.10
Purchase #2	$189.69	10.604%	$209.8047	$209.80	$209.80	$209.80
Purchase #3	$61.47	7.840%	$66.2892	$66.29	$66.30	$66.30
Purchase #4	$103.60	5.732%	$109.5384	$109.54	$109.55	$109.50
Purchase #5	$224.61	7.678%	$241.8556	$241.86	$241.85	$241.90
Purchase #6	$118.56	8.389%	$128.506	$128.51	$128.50	$128.50
Purchase #7	$205.55	7.215%	$220.3804	$220.38	$220.40	$220.40
7 purchase totals =	$973.43		$1,052.4834	$1,052.49	$1,052.50	$1,052.50