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	$108.58	3.473%	$112.351	$112.35	$112.35	$112.40
Purchase #2	$92.37	6.722%	$98.5791	$98.58	$98.60	$98.60
Purchase #3	$208.96	3.704%	$216.6999	$216.70	$216.70	$216.70
Purchase #4	$34.70	7.139%	$37.1772	$37.18	$37.20	$37.20
Purchase #5	$31.34	13.808%	$35.6674	$35.67	$35.65	$35.70
Purchase #6	$16.89	11.669%	$18.8609	$18.86	$18.85	$18.90
Purchase #7	$185.31	3.550%	$191.8885	$191.89	$191.90	$191.90
7 purchase totals =	$678.15		$711.2240	$711.23	$711.25	$711.40