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	$196.58	8.246%	$212.79	$212.79	$212.80	$212.80
Purchase #2	$75.36	9.189%	$82.2848	$82.28	$82.30	$82.30
Purchase #3	$175.85	6.331%	$186.9831	$186.98	$187.00	$187.00
Purchase #4	$174.32	11.873%	$195.017	$195.02	$195.00	$195.00
Purchase #5	$118.28	4.583%	$123.7008	$123.70	$123.70	$123.70
Purchase #6	$51.82	5.824%	$54.838	$54.84	$54.85	$54.80
Purchase #7	$131.54	13.193%	$148.8941	$148.89	$148.90	$148.90
7 purchase totals =	$923.75		$1,004.5078	$1,004.50	$1,004.55	$1,004.50