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	$157.65	7.532%	$169.5242	$169.52	$169.50	$169.50
Purchase #2	$44.90	8.170%	$48.5683	$48.57	$48.55	$48.60
Purchase #3	$184.58	10.812%	$204.5368	$204.54	$204.55	$204.50
Purchase #4	$111.49	7.300%	$119.6288	$119.63	$119.65	$119.60
Purchase #5	$142.45	10.115%	$156.8588	$156.86	$156.85	$156.90
Purchase #6	$28.97	8.552%	$31.4475	$31.45	$31.45	$31.40
Purchase #7	$211.83	5.693%	$223.8895	$223.89	$223.90	$223.90
7 purchase totals =	$881.87		$954.4539	$954.46	$954.45	$954.40