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	$124.62	7.445%	$133.898	$133.90	$133.90	$133.90
Purchase #2	$193.63	3.296%	$200.012	$200.01	$200.00	$200.00
Purchase #3	$88.60	12.737%	$99.885	$99.89	$99.90	$99.90
Purchase #4	$179.33	6.268%	$190.5704	$190.57	$190.55	$190.60
Purchase #5	$160.80	3.413%	$166.2881	$166.29	$166.30	$166.30
Purchase #6	$108.98	13.417%	$123.6018	$123.60	$123.60	$123.60
Purchase #7	$55.26	12.716%	$62.2869	$62.29	$62.30	$62.30
7 purchase totals =	$911.22		$976.5422	$976.55	$976.55	$976.60