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	$55.73	10.801%	$61.7494	$61.75	$61.75	$61.70
Purchase #2	$67.43	7.248%	$72.3173	$72.32	$72.30	$72.30
Purchase #3	$236.56	9.247%	$258.4347	$258.43	$258.45	$258.40
Purchase #4	$245.57	7.524%	$264.0467	$264.05	$264.05	$264.00
Purchase #5	$216.31	7.170%	$231.8194	$231.82	$231.80	$231.80
Purchase #6	$217.98	6.685%	$232.552	$232.55	$232.55	$232.60
Purchase #7	$35.46	8.825%	$38.5893	$38.59	$38.60	$38.60
7 purchase totals =	$1,075.04		$1,159.5088	$1,159.51	$1,159.50	$1,159.40