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	$196.59	10.147%	$216.538	$216.54	$216.55	$216.50
Purchase #2	$178.91	7.535%	$192.3909	$192.39	$192.40	$192.40
Purchase #3	$106.75	9.470%	$116.8592	$116.86	$116.85	$116.90
Purchase #4	$206.72	4.640%	$216.3118	$216.31	$216.30	$216.30
Purchase #5	$196.78	7.623%	$211.7805	$211.78	$211.80	$211.80
Purchase #6	$142.43	12.451%	$160.164	$160.16	$160.15	$160.20
Purchase #7	$52.41	5.276%	$55.1752	$55.18	$55.20	$55.20
7 purchase totals =	$1,080.59		$1,169.2196	$1,169.22	$1,169.25	$1,169.30