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	$201.71	5.850%	$213.51	$213.51	$213.50	$213.50
Purchase #2	$59.57	4.376%	$62.1768	$62.18	$62.20	$62.20
Purchase #3	$143.57	6.175%	$152.4354	$152.44	$152.45	$152.40
Purchase #4	$196.72	13.606%	$223.4857	$223.49	$223.50	$223.50
Purchase #5	$213.89	8.741%	$232.5861	$232.59	$232.60	$232.60
Purchase #6	$141.68	6.438%	$150.8014	$150.80	$150.80	$150.80
Purchase #7	$94.48	5.756%	$99.9183	$99.92	$99.90	$99.90
7 purchase totals =	$1,051.62		$1,134.9137	$1,134.93	$1,134.95	$1,134.90