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	$196.76	6.673%	$209.8898	$209.89	$209.90	$209.90
Purchase #2	$180.26	4.488%	$188.3501	$188.35	$188.35	$188.40
Purchase #3	$194.82	5.656%	$205.839	$205.84	$205.85	$205.80
Purchase #4	$205.36	11.634%	$229.2516	$229.25	$229.25	$229.30
Purchase #5	$195.43	10.259%	$215.4792	$215.48	$215.50	$215.50
Purchase #6	$243.32	12.627%	$274.044	$274.04	$274.05	$274.00
Purchase #7	$107.64	4.854%	$112.8648	$112.86	$112.85	$112.90
7 purchase totals =	$1,323.59		$1,435.7185	$1,435.71	$1,435.75	$1,435.80