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	$47.28	12.818%	$53.3404	$53.34	$53.35	$53.30
Purchase #2	$215.99	13.393%	$244.9175	$244.92	$244.90	$244.90
Purchase #3	$119.80	4.304%	$124.9562	$124.96	$124.95	$125.00
Purchase #4	$89.32	13.756%	$101.6069	$101.61	$101.60	$101.60
Purchase #5	$149.50	5.501%	$157.724	$157.72	$157.70	$157.70
Purchase #6	$177.57	13.142%	$200.9062	$200.91	$200.90	$200.90
Purchase #7	$157.33	9.347%	$172.0356	$172.04	$172.05	$172.00
7 purchase totals =	$956.79		$1,055.4868	$1,055.50	$1,055.45	$1,055.40