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	$85.83	7.195%	$92.0055	$92.01	$92.00	$92.00
Purchase #2	$55.77	7.215%	$59.7938	$59.79	$59.80	$59.80
Purchase #3	$44.51	8.837%	$48.4433	$48.44	$48.45	$48.40
Purchase #4	$244.96	11.847%	$273.9804	$273.98	$274.00	$274.00
Purchase #5	$153.69	3.378%	$158.8816	$158.88	$158.90	$158.90
Purchase #6	$64.84	13.319%	$73.476	$73.48	$73.50	$73.50
Purchase #7	$16.31	3.143%	$16.8226	$16.82	$16.80	$16.80
7 purchase totals =	$665.91		$723.4032	$723.40	$723.45	$723.40