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	$182.26	10.182%	$200.8177	$200.82	$200.80	$200.80
Purchase #2	$238.46	4.534%	$249.2718	$249.27	$249.25	$249.30
Purchase #3	$206.55	4.824%	$216.514	$216.51	$216.50	$216.50
Purchase #4	$196.45	13.864%	$223.6858	$223.69	$223.70	$223.70
Purchase #5	$42.99	6.585%	$45.8209	$45.82	$45.80	$45.80
Purchase #6	$218.80	10.698%	$242.2072	$242.21	$242.20	$242.20
Purchase #7	$218.64	6.293%	$232.399	$232.40	$232.40	$232.40
7 purchase totals =	$1,304.15		$1,410.7164	$1,410.72	$1,410.65	$1,410.70