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	$73.63	4.541%	$76.9735	$76.97	$76.95	$77.00
Purchase #2	$247.47	7.586%	$266.2431	$266.24	$266.25	$266.20
Purchase #3	$168.47	7.677%	$181.4034	$181.40	$181.40	$181.40
Purchase #4	$63.50	12.426%	$71.3905	$71.39	$71.40	$71.40
Purchase #5	$225.52	13.239%	$255.3766	$255.38	$255.40	$255.40
Purchase #6	$149.80	5.796%	$158.4824	$158.48	$158.50	$158.50
Purchase #7	$38.71	4.245%	$40.3532	$40.35	$40.35	$40.40
7 purchase totals =	$967.10		$1,050.2227	$1,050.21	$1,050.25	$1,050.30