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	$87.96	10.148%	$96.8862	$96.89	$96.90	$96.90
Purchase #2	$61.57	9.299%	$67.2954	$67.30	$67.30	$67.30
Purchase #3	$46.45	3.396%	$48.0274	$48.03	$48.05	$48.00
Purchase #4	$78.53	12.669%	$88.479	$88.48	$88.50	$88.50
Purchase #5	$162.52	6.646%	$173.3211	$173.32	$173.30	$173.30
Purchase #6	$207.70	5.507%	$219.138	$219.14	$219.15	$219.10
Purchase #7	$40.64	5.571%	$42.9041	$42.90	$42.90	$42.90
7 purchase totals =	$685.37		$736.0512	$736.06	$736.10	$736.00