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	$176.44	11.381%	$196.5206	$196.52	$196.50	$196.50
Purchase #2	$210.54	7.763%	$226.8842	$226.88	$226.90	$226.90
Purchase #3	$46.68	4.128%	$48.607	$48.61	$48.60	$48.60
Purchase #4	$195.37	7.773%	$210.5561	$210.56	$210.55	$210.60
Purchase #5	$102.80	12.411%	$115.5585	$115.56	$115.55	$115.60
Purchase #6	$28.94	11.494%	$32.2664	$32.27	$32.25	$32.30
Purchase #7	$104.62	7.826%	$112.8076	$112.81	$112.80	$112.80
7 purchase totals =	$865.39		$943.2004	$943.21	$943.15	$943.30