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	$119.43	3.567%	$123.6901	$123.69	$123.70	$123.70
Purchase #2	$238.74	4.843%	$250.3022	$250.30	$250.30	$250.30
Purchase #3	$231.45	13.840%	$263.4827	$263.48	$263.50	$263.50
Purchase #4	$79.51	4.165%	$82.8216	$82.82	$82.80	$82.80
Purchase #5	$55.85	8.799%	$60.7642	$60.76	$60.75	$60.80
Purchase #6	$160.66	7.792%	$173.1786	$173.18	$173.20	$173.20
Purchase #7	$241.76	8.611%	$262.578	$262.58	$262.60	$262.60
7 purchase totals =	$1,127.40		$1,216.8174	$1,216.81	$1,216.85	$1,216.90