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	$233.25	3.615%	$241.682	$241.68	$241.70	$241.70
Purchase #2	$69.37	5.859%	$73.4344	$73.43	$73.45	$73.40
Purchase #3	$94.37	5.306%	$99.3773	$99.38	$99.40	$99.40
Purchase #4	$219.65	9.198%	$239.8534	$239.85	$239.85	$239.90
Purchase #5	$36.45	11.209%	$40.5357	$40.54	$40.55	$40.50
Purchase #6	$80.45	12.489%	$90.4974	$90.50	$90.50	$90.50
Purchase #7	$206.50	12.435%	$232.1783	$232.18	$232.20	$232.20
7 purchase totals =	$940.04		$1,017.5585	$1,017.56	$1,017.65	$1,017.60