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	$126.33	3.323%	$130.5279	$130.53	$130.55	$130.50
Purchase #2	$27.77	13.786%	$31.5984	$31.60	$31.60	$31.60
Purchase #3	$191.82	4.599%	$200.6418	$200.64	$200.65	$200.60
Purchase #4	$50.59	12.270%	$56.7974	$56.80	$56.80	$56.80
Purchase #5	$167.43	3.665%	$173.5663	$173.57	$173.55	$173.60
Purchase #6	$239.61	10.561%	$264.9152	$264.92	$264.90	$264.90
Purchase #7	$65.72	3.721%	$68.1654	$68.17	$68.15	$68.20
7 purchase totals =	$869.27		$926.2124	$926.23	$926.20	$926.20