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	$114.38	10.493%	$126.3819	$126.38	$126.40	$126.40
Purchase #2	$195.57	13.291%	$221.5632	$221.56	$221.55	$221.60
Purchase #3	$68.66	5.660%	$72.5462	$72.55	$72.55	$72.50
Purchase #4	$76.28	13.437%	$86.5297	$86.53	$86.55	$86.50
Purchase #5	$137.58	7.498%	$147.8957	$147.90	$147.90	$147.90
Purchase #6	$90.82	9.470%	$99.4207	$99.42	$99.40	$99.40
Purchase #7	$166.68	12.443%	$187.42	$187.42	$187.40	$187.40
7 purchase totals =	$849.97		$941.7574	$941.76	$941.75	$941.70