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	$12.88	12.238%	$14.4563	$14.46	$14.45	$14.50
Purchase #2	$245.57	7.385%	$263.7053	$263.71	$263.70	$263.70
Purchase #3	$216.72	13.747%	$246.5125	$246.51	$246.50	$246.50
Purchase #4	$56.86	7.727%	$61.2536	$61.25	$61.25	$61.30
Purchase #5	$92.60	4.604%	$96.8633	$96.86	$96.85	$96.90
Purchase #6	$203.43	7.437%	$218.5591	$218.56	$218.55	$218.60
Purchase #7	$36.73	9.691%	$40.2895	$40.29	$40.30	$40.30
7 purchase totals =	$864.79		$941.6396	$941.64	$941.60	$941.80