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	$152.89	5.221%	$160.8724	$160.87	$160.85	$160.90
Purchase #2	$13.93	13.833%	$15.8569	$15.86	$15.85	$15.90
Purchase #3	$134.49	13.122%	$152.1378	$152.14	$152.15	$152.10
Purchase #4	$160.59	10.364%	$177.2335	$177.23	$177.25	$177.20
Purchase #5	$243.76	4.856%	$255.597	$255.60	$255.60	$255.60
Purchase #6	$202.45	11.690%	$226.1164	$226.12	$226.10	$226.10
Purchase #7	$35.43	5.556%	$37.3985	$37.40	$37.40	$37.40
7 purchase totals =	$943.54		$1,025.2125	$1,025.22	$1,025.20	$1,025.20