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	$147.60	13.802%	$167.9718	$167.97	$167.95	$168.00
Purchase #2	$51.46	12.499%	$57.892	$57.89	$57.90	$57.90
Purchase #3	$76.40	9.721%	$83.8268	$83.83	$83.85	$83.80
Purchase #4	$209.28	5.544%	$220.8825	$220.88	$220.90	$220.90
Purchase #5	$231.79	13.436%	$262.9333	$262.93	$262.95	$262.90
Purchase #6	$139.41	3.178%	$143.8404	$143.84	$143.85	$143.80
Purchase #7	$210.79	5.513%	$222.4109	$222.41	$222.40	$222.40
7 purchase totals =	$1,066.73		$1,159.7577	$1,159.75	$1,159.80	$1,159.70