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	$158.75	5.365%	$167.2669	$167.27	$167.25	$167.30
Purchase #2	$5.67	3.403%	$5.863	$5.86	$5.85	$5.90
Purchase #3	$245.73	3.482%	$254.2863	$254.29	$254.30	$254.30
Purchase #4	$48.80	12.623%	$54.96	$54.96	$54.95	$55.00
Purchase #5	$30.60	10.563%	$33.8323	$33.83	$33.85	$33.80
Purchase #6	$158.69	12.492%	$178.5136	$178.51	$178.50	$178.50
Purchase #7	$149.72	12.797%	$168.8797	$168.88	$168.90	$168.90
7 purchase totals =	$797.96		$863.6018	$863.60	$863.60	$863.70