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	$215.64	5.443%	$227.3773	$227.38	$227.40	$227.40
Purchase #2	$42.26	12.330%	$47.4707	$47.47	$47.45	$47.50
Purchase #3	$243.94	4.854%	$255.7808	$255.78	$255.80	$255.80
Purchase #4	$86.52	10.191%	$95.3373	$95.34	$95.35	$95.30
Purchase #5	$67.53	6.466%	$71.8965	$71.90	$71.90	$71.90
Purchase #6	$191.80	4.857%	$201.1157	$201.12	$201.10	$201.10
Purchase #7	$186.76	6.465%	$198.834	$198.83	$198.85	$198.80
7 purchase totals =	$1,034.45		$1,097.8123	$1,097.82	$1,097.85	$1,097.80