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	$194.70	11.326%	$216.7517	$216.75	$216.75	$216.80
Purchase #2	$38.36	11.154%	$42.6387	$42.64	$42.65	$42.60
Purchase #3	$112.53	9.440%	$123.1528	$123.15	$123.15	$123.20
Purchase #4	$149.63	5.440%	$157.7699	$157.77	$157.75	$157.80
Purchase #5	$132.72	12.604%	$149.448	$149.45	$149.45	$149.40
Purchase #6	$143.77	11.828%	$160.7751	$160.78	$160.80	$160.80
Purchase #7	$152.36	8.807%	$165.7783	$165.78	$165.80	$165.80
7 purchase totals =	$924.07		$1,016.3145	$1,016.32	$1,016.35	$1,016.40