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	$187.90	4.125%	$195.6509	$195.65	$195.65	$195.70
Purchase #2	$19.96	7.385%	$21.434	$21.43	$21.45	$21.40
Purchase #3	$92.90	8.148%	$100.4695	$100.47	$100.45	$100.50
Purchase #4	$235.49	13.656%	$267.6485	$267.65	$267.65	$267.60
Purchase #5	$125.50	4.482%	$131.1249	$131.12	$131.10	$131.10
Purchase #6	$167.66	6.704%	$178.8999	$178.90	$178.90	$178.90
Purchase #7	$217.53	8.808%	$236.69	$236.69	$236.70	$236.70
7 purchase totals =	$1,046.94		$1,131.9177	$1,131.91	$1,131.90	$1,131.90