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	$189.28	3.587%	$196.0695	$196.07	$196.05	$196.10
Purchase #2	$114.94	4.493%	$120.1043	$120.10	$120.10	$120.10
Purchase #3	$148.81	13.328%	$168.6434	$168.64	$168.65	$168.60
Purchase #4	$118.72	13.634%	$134.9063	$134.91	$134.90	$134.90
Purchase #5	$23.28	10.118%	$25.6355	$25.64	$25.65	$25.60
Purchase #6	$133.35	9.665%	$146.2383	$146.24	$146.25	$146.20
Purchase #7	$234.96	3.171%	$242.4106	$242.41	$242.40	$242.40
7 purchase totals =	$963.34		$1,034.0079	$1,034.01	$1,034.00	$1,033.90