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	$155.38	4.409%	$162.2307	$162.23	$162.25	$162.20
Purchase #2	$152.72	4.407%	$159.4504	$159.45	$159.45	$159.50
Purchase #3	$132.96	6.874%	$142.0997	$142.10	$142.10	$142.10
Purchase #4	$34.60	5.112%	$36.3688	$36.37	$36.35	$36.40
Purchase #5	$38.76	8.687%	$42.1271	$42.13	$42.15	$42.10
Purchase #6	$204.51	11.730%	$228.499	$228.50	$228.50	$228.50
Purchase #7	$235.81	11.355%	$262.5862	$262.59	$262.60	$262.60
7 purchase totals =	$954.74		$1,033.3619	$1,033.37	$1,033.40	$1,033.40