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	$90.97	4.272%	$94.8562	$94.86	$94.85	$94.90
Purchase #2	$172.56	13.556%	$195.9522	$195.95	$195.95	$196.00
Purchase #3	$175.49	9.118%	$191.4912	$191.49	$191.50	$191.50
Purchase #4	$89.46	10.233%	$98.6144	$98.61	$98.60	$98.60
Purchase #5	$81.69	10.395%	$90.1817	$90.18	$90.20	$90.20
Purchase #6	$86.84	10.103%	$95.6134	$95.61	$95.60	$95.60
Purchase #7	$148.57	13.435%	$168.5304	$168.53	$168.55	$168.50
7 purchase totals =	$845.58		$935.2395	$935.23	$935.25	$935.30