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	$194.39	9.351%	$212.5674	$212.57	$212.55	$212.60
Purchase #2	$115.25	12.469%	$129.6205	$129.62	$129.60	$129.60
Purchase #3	$13.28	10.257%	$14.6421	$14.64	$14.65	$14.60
Purchase #4	$54.78	9.320%	$59.8855	$59.89	$59.90	$59.90
Purchase #5	$182.98	9.739%	$200.8004	$200.80	$200.80	$200.80
Purchase #6	$154.50	9.111%	$168.5765	$168.58	$168.60	$168.60
Purchase #7	$216.90	7.370%	$232.8855	$232.89	$232.90	$232.90
7 purchase totals =	$932.08		$1,018.9779	$1,018.99	$1,019.00	$1,019.00