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	$184.57	8.436%	$200.1403	$200.14	$200.15	$200.10
Purchase #2	$64.99	10.874%	$72.057	$72.06	$72.05	$72.10
Purchase #3	$57.31	3.144%	$59.1118	$59.11	$59.10	$59.10
Purchase #4	$227.68	13.538%	$258.5033	$258.50	$258.50	$258.50
Purchase #5	$34.47	7.319%	$36.9929	$36.99	$37.00	$37.00
Purchase #6	$241.97	3.141%	$249.5703	$249.57	$249.55	$249.60
Purchase #7	$175.48	13.481%	$199.1365	$199.14	$199.15	$199.10
7 purchase totals =	$986.47		$1,075.5121	$1,075.51	$1,075.50	$1,075.50