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	$126.76	12.500%	$142.605	$142.61	$142.60	$142.60
Purchase #2	$213.40	9.285%	$233.2142	$233.21	$233.20	$233.20
Purchase #3	$173.56	3.419%	$179.494	$179.49	$179.50	$179.50
Purchase #4	$218.93	8.676%	$237.9244	$237.92	$237.90	$237.90
Purchase #5	$98.56	5.373%	$103.8556	$103.86	$103.85	$103.90
Purchase #6	$51.62	5.815%	$54.6217	$54.62	$54.60	$54.60
Purchase #7	$164.80	5.365%	$173.6415	$173.64	$173.65	$173.60
7 purchase totals =	$1,047.63		$1,125.3564	$1,125.35	$1,125.30	$1,125.30