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	$62.90	5.323%	$66.2482	$66.25	$66.25	$66.20
Purchase #2	$113.25	5.767%	$119.7811	$119.78	$119.80	$119.80
Purchase #3	$115.99	10.310%	$127.9486	$127.95	$127.95	$127.90
Purchase #4	$198.80	9.847%	$218.3758	$218.38	$218.40	$218.40
Purchase #5	$214.69	12.519%	$241.567	$241.57	$241.55	$241.60
Purchase #6	$160.93	13.362%	$182.4335	$182.43	$182.45	$182.40
Purchase #7	$61.75	7.281%	$66.246	$66.25	$66.25	$66.20
7 purchase totals =	$928.31		$1,022.6002	$1,022.61	$1,022.65	$1,022.50