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	$242.29	8.136%	$262.0027	$262.00	$262.00	$262.00
Purchase #2	$112.72	7.586%	$121.2709	$121.27	$121.25	$121.30
Purchase #3	$151.56	3.349%	$156.6357	$156.64	$156.65	$156.60
Purchase #4	$184.42	6.686%	$196.7503	$196.75	$196.75	$196.80
Purchase #5	$61.88	10.854%	$68.5965	$68.60	$68.60	$68.60
Purchase #6	$164.86	8.150%	$178.2961	$178.30	$178.30	$178.30
Purchase #7	$133.41	13.391%	$151.2749	$151.27	$151.25	$151.30
7 purchase totals =	$1,051.14		$1,134.8271	$1,134.83	$1,134.80	$1,134.90