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	$200.70	9.319%	$219.4032	$219.40	$219.40	$219.40
Purchase #2	$172.38	10.717%	$190.854	$190.85	$190.85	$190.90
Purchase #3	$98.75	5.733%	$104.4113	$104.41	$104.40	$104.40
Purchase #4	$176.43	4.739%	$184.791	$184.79	$184.80	$184.80
Purchase #5	$127.54	11.781%	$142.5655	$142.57	$142.55	$142.60
Purchase #6	$13.74	4.774%	$14.3959	$14.40	$14.40	$14.40
Purchase #7	$160.94	5.298%	$169.4666	$169.47	$169.45	$169.50
7 purchase totals =	$950.48		$1,025.8875	$1,025.89	$1,025.85	$1,026.00