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	$118.49	7.162%	$126.9763	$126.98	$127.00	$127.00
Purchase #2	$17.45	6.561%	$18.5949	$18.59	$18.60	$18.60
Purchase #3	$88.86	10.639%	$98.3138	$98.31	$98.30	$98.30
Purchase #4	$77.37	6.717%	$82.5669	$82.57	$82.55	$82.60
Purchase #5	$103.58	5.144%	$108.9082	$108.91	$108.90	$108.90
Purchase #6	$118.79	4.330%	$123.9336	$123.93	$123.95	$123.90
Purchase #7	$171.64	12.626%	$193.3113	$193.31	$193.30	$193.30
7 purchase totals =	$696.18		$752.6050	$752.60	$752.60	$752.60