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	$140.77	7.333%	$151.0927	$151.09	$151.10	$151.10
Purchase #2	$73.72	7.709%	$79.4031	$79.40	$79.40	$79.40
Purchase #3	$184.41	11.134%	$204.9422	$204.94	$204.95	$204.90
Purchase #4	$241.49	13.842%	$274.917	$274.92	$274.90	$274.90
Purchase #5	$96.72	3.587%	$100.1893	$100.19	$100.20	$100.20
Purchase #6	$163.77	3.141%	$168.914	$168.91	$168.90	$168.90
Purchase #7	$113.30	5.827%	$119.902	$119.90	$119.90	$119.90
7 purchase totals =	$1,014.18		$1,099.3603	$1,099.35	$1,099.35	$1,099.30