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	$149.38	13.765%	$169.9422	$169.94	$169.95	$169.90
Purchase #2	$89.84	8.447%	$97.4288	$97.43	$97.45	$97.40
Purchase #3	$116.53	8.535%	$126.4758	$126.48	$126.50	$126.50
Purchase #4	$173.57	13.241%	$196.5524	$196.55	$196.55	$196.60
Purchase #5	$27.36	8.410%	$29.661	$29.66	$29.65	$29.70
Purchase #6	$237.28	10.820%	$262.9537	$262.95	$262.95	$263.00
Purchase #7	$145.56	3.604%	$150.806	$150.81	$150.80	$150.80
7 purchase totals =	$939.52		$1,033.8199	$1,033.82	$1,033.85	$1,033.90