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	$67.55	6.332%	$71.8273	$71.83	$71.85	$71.80
Purchase #2	$94.50	5.638%	$99.8279	$99.83	$99.85	$99.80
Purchase #3	$204.39	8.620%	$222.0084	$222.01	$222.00	$222.00
Purchase #4	$246.58	7.654%	$265.4532	$265.45	$265.45	$265.50
Purchase #5	$233.70	3.104%	$240.954	$240.95	$240.95	$241.00
Purchase #6	$227.74	12.628%	$256.499	$256.50	$256.50	$256.50
Purchase #7	$30.88	6.561%	$32.906	$32.91	$32.90	$32.90
7 purchase totals =	$1,105.34		$1,189.4758	$1,189.48	$1,189.50	$1,189.50