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	$161.30	3.814%	$167.452	$167.45	$167.45	$167.50
Purchase #2	$220.47	8.124%	$238.381	$238.38	$238.40	$238.40
Purchase #3	$104.86	6.372%	$111.5417	$111.54	$111.55	$111.50
Purchase #4	$80.73	10.128%	$88.9063	$88.91	$88.90	$88.90
Purchase #5	$248.69	11.294%	$276.777	$276.78	$276.80	$276.80
Purchase #6	$139.31	9.840%	$153.0181	$153.02	$153.00	$153.00
Purchase #7	$206.26	10.485%	$227.8864	$227.89	$227.90	$227.90
7 purchase totals =	$1,161.62		$1,263.9625	$1,263.97	$1,264.00	$1,264.00