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	$111.96	6.359%	$119.0795	$119.08	$119.10	$119.10
Purchase #2	$19.76	10.652%	$21.8648	$21.86	$21.85	$21.90
Purchase #3	$88.61	13.835%	$100.8692	$100.87	$100.85	$100.90
Purchase #4	$33.32	6.796%	$35.5844	$35.58	$35.60	$35.60
Purchase #5	$246.85	5.778%	$261.113	$261.11	$261.10	$261.10
Purchase #6	$216.54	5.758%	$229.0084	$229.01	$229.00	$229.00
Purchase #7	$244.54	4.517%	$255.5859	$255.59	$255.60	$255.60
7 purchase totals =	$961.58		$1,023.1052	$1,023.10	$1,023.10	$1,023.20