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	$184.53	6.716%	$196.923	$196.92	$196.90	$196.90
Purchase #2	$179.63	5.567%	$189.63	$189.63	$189.65	$189.60
Purchase #3	$218.50	12.497%	$245.8059	$245.81	$245.80	$245.80
Purchase #4	$84.80	5.691%	$89.626	$89.63	$89.65	$89.60
Purchase #5	$63.53	9.523%	$69.58	$69.58	$69.60	$69.60
Purchase #6	$147.69	4.343%	$154.1042	$154.10	$154.10	$154.10
Purchase #7	$77.49	4.358%	$80.867	$80.87	$80.85	$80.90
7 purchase totals =	$956.17		$1,026.5361	$1,026.54	$1,026.55	$1,026.50