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	$38.94	12.265%	$43.716	$43.72	$43.70	$43.70
Purchase #2	$147.78	3.151%	$152.4365	$152.44	$152.45	$152.40
Purchase #3	$145.68	9.767%	$159.9086	$159.91	$159.90	$159.90
Purchase #4	$166.60	11.436%	$185.6524	$185.65	$185.65	$185.70
Purchase #5	$103.64	7.870%	$111.7965	$111.80	$111.80	$111.80
Purchase #6	$132.60	7.730%	$142.85	$142.85	$142.85	$142.90
Purchase #7	$213.74	11.222%	$237.7259	$237.73	$237.75	$237.70
7 purchase totals =	$948.98		$1,034.0859	$1,034.10	$1,034.10	$1,034.10