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	$213.85	5.364%	$225.3209	$225.32	$225.30	$225.30
Purchase #2	$55.86	9.177%	$60.9863	$60.99	$61.00	$61.00
Purchase #3	$150.81	10.431%	$166.541	$166.54	$166.55	$166.50
Purchase #4	$158.77	6.635%	$169.3044	$169.30	$169.30	$169.30
Purchase #5	$35.66	7.395%	$38.2971	$38.30	$38.30	$38.30
Purchase #6	$244.47	6.273%	$259.8056	$259.81	$259.80	$259.80
Purchase #7	$194.47	6.366%	$206.85	$206.85	$206.85	$206.90
7 purchase totals =	$1,053.89		$1,127.1053	$1,127.11	$1,127.10	$1,127.10