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	$86.79	10.151%	$95.6001	$95.60	$95.60	$95.60
Purchase #2	$40.83	3.216%	$42.1431	$42.14	$42.15	$42.10
Purchase #3	$167.33	5.150%	$175.9475	$175.95	$175.95	$175.90
Purchase #4	$37.46	13.536%	$42.5306	$42.53	$42.55	$42.50
Purchase #5	$93.25	12.834%	$105.2177	$105.22	$105.20	$105.20
Purchase #6	$234.87	5.851%	$248.6122	$248.61	$248.60	$248.60
Purchase #7	$8.47	3.203%	$8.7413	$8.74	$8.75	$8.70
7 purchase totals =	$669.00		$718.7925	$718.79	$718.80	$718.60