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	$41.98	9.807%	$46.097	$46.10	$46.10	$46.10
Purchase #2	$74.26	12.281%	$83.3799	$83.38	$83.40	$83.40
Purchase #3	$159.45	4.826%	$167.1451	$167.15	$167.15	$167.10
Purchase #4	$178.70	7.858%	$192.7422	$192.74	$192.75	$192.70
Purchase #5	$152.62	10.612%	$168.816	$168.82	$168.80	$168.80
Purchase #6	$239.32	5.254%	$251.8939	$251.89	$251.90	$251.90
Purchase #7	$96.50	4.323%	$100.6717	$100.67	$100.65	$100.70
7 purchase totals =	$942.83		$1,010.7458	$1,010.75	$1,010.75	$1,010.70