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	$56.81	7.336%	$60.9776	$60.98	$61.00	$61.00
Purchase #2	$165.29	12.470%	$185.9017	$185.90	$185.90	$185.90
Purchase #3	$137.83	4.491%	$144.0199	$144.02	$144.00	$144.00
Purchase #4	$34.48	6.164%	$36.6053	$36.61	$36.60	$36.60
Purchase #5	$91.89	3.803%	$95.3846	$95.38	$95.40	$95.40
Purchase #6	$165.38	9.320%	$180.7934	$180.79	$180.80	$180.80
Purchase #7	$201.36	10.426%	$222.3538	$222.35	$222.35	$222.40
7 purchase totals =	$853.04		$926.0363	$926.03	$926.05	$926.10