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	$173.62	13.240%	$196.6073	$196.61	$196.60	$196.60
Purchase #2	$144.96	3.603%	$150.1829	$150.18	$150.20	$150.20
Purchase #3	$22.83	7.582%	$24.561	$24.56	$24.55	$24.60
Purchase #4	$69.30	5.195%	$72.9001	$72.90	$72.90	$72.90
Purchase #5	$158.39	12.527%	$178.2315	$178.23	$178.25	$178.20
Purchase #6	$35.71	4.614%	$37.3577	$37.36	$37.35	$37.40
Purchase #7	$59.80	5.792%	$63.2636	$63.26	$63.25	$63.30
7 purchase totals =	$664.61		$723.1041	$723.10	$723.10	$723.20