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	$143.59	3.513%	$148.6343	$148.63	$148.65	$148.60
Purchase #2	$144.25	13.417%	$163.604	$163.60	$163.60	$163.60
Purchase #3	$175.32	6.332%	$186.4213	$186.42	$186.40	$186.40
Purchase #4	$86.36	4.378%	$90.1408	$90.14	$90.15	$90.10
Purchase #5	$59.97	4.770%	$62.8306	$62.83	$62.85	$62.80
Purchase #6	$168.77	12.743%	$190.2764	$190.28	$190.30	$190.30
Purchase #7	$163.47	3.168%	$168.6487	$168.65	$168.65	$168.60
7 purchase totals =	$941.73		$1,010.5561	$1,010.55	$1,010.60	$1,010.40