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	$115.93	3.452%	$119.9319	$119.93	$119.95	$119.90
Purchase #2	$10.25	13.219%	$11.6049	$11.60	$11.60	$11.60
Purchase #3	$65.89	8.498%	$71.4893	$71.49	$71.50	$71.50
Purchase #4	$59.63	4.765%	$62.4714	$62.47	$62.45	$62.50
Purchase #5	$238.74	10.688%	$264.2565	$264.26	$264.25	$264.30
Purchase #6	$59.68	7.662%	$64.2527	$64.25	$64.25	$64.30
Purchase #7	$108.81	8.785%	$118.369	$118.37	$118.35	$118.40
7 purchase totals =	$658.93		$712.3757	$712.37	$712.35	$712.50