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	$207.47	3.407%	$214.5385	$214.54	$214.55	$214.50
Purchase #2	$216.34	11.104%	$240.3624	$240.36	$240.35	$240.40
Purchase #3	$119.55	10.224%	$131.7728	$131.77	$131.75	$131.80
Purchase #4	$79.48	9.245%	$86.8279	$86.83	$86.85	$86.80
Purchase #5	$17.32	6.833%	$18.5035	$18.50	$18.50	$18.50
Purchase #6	$222.80	7.774%	$240.1205	$240.12	$240.10	$240.10
Purchase #7	$248.62	10.115%	$273.7679	$273.77	$273.75	$273.80
7 purchase totals =	$1,111.58		$1,205.8935	$1,205.89	$1,205.85	$1,205.90