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	$86.82	10.775%	$96.1749	$96.17	$96.15	$96.20
Purchase #2	$216.78	8.495%	$235.1955	$235.20	$235.20	$235.20
Purchase #3	$64.56	10.210%	$71.1516	$71.15	$71.15	$71.20
Purchase #4	$37.47	3.496%	$38.78	$38.78	$38.80	$38.80
Purchase #5	$248.28	12.109%	$278.3442	$278.34	$278.35	$278.30
Purchase #6	$121.51	4.178%	$126.5867	$126.59	$126.60	$126.60
Purchase #7	$248.48	4.507%	$259.679	$259.68	$259.70	$259.70
7 purchase totals =	$1,023.90		$1,105.9119	$1,105.91	$1,105.95	$1,106.00