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	$121.94	7.475%	$131.055	$131.06	$131.05	$131.10
Purchase #2	$32.71	12.829%	$36.9064	$36.91	$36.90	$36.90
Purchase #3	$141.56	8.526%	$153.6294	$153.63	$153.65	$153.60
Purchase #4	$156.61	10.483%	$173.0274	$173.03	$173.05	$173.00
Purchase #5	$222.46	8.399%	$241.1444	$241.14	$241.15	$241.10
Purchase #6	$219.89	8.601%	$238.8027	$238.80	$238.80	$238.80
Purchase #7	$89.60	6.426%	$95.3577	$95.36	$95.35	$95.40
7 purchase totals =	$984.77		$1,069.9230	$1,069.93	$1,069.95	$1,069.90