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	$181.32	13.745%	$206.2424	$206.24	$206.25	$206.20
Purchase #2	$215.43	10.595%	$238.2548	$238.25	$238.25	$238.30
Purchase #3	$33.61	10.854%	$37.258	$37.26	$37.25	$37.30
Purchase #4	$158.65	3.743%	$164.5883	$164.59	$164.60	$164.60
Purchase #5	$149.34	6.234%	$158.6499	$158.65	$158.65	$158.60
Purchase #6	$144.60	8.726%	$157.2178	$157.22	$157.20	$157.20
Purchase #7	$86.66	4.799%	$90.8188	$90.82	$90.80	$90.80
7 purchase totals =	$969.61		$1,053.0300	$1,053.03	$1,053.00	$1,053.00