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	$208.43	9.130%	$227.4597	$227.46	$227.45	$227.50
Purchase #2	$40.47	4.339%	$42.226	$42.23	$42.25	$42.20
Purchase #3	$203.54	3.465%	$210.5927	$210.59	$210.60	$210.60
Purchase #4	$117.77	5.333%	$124.0507	$124.05	$124.05	$124.10
Purchase #5	$223.74	4.269%	$233.2915	$233.29	$233.30	$233.30
Purchase #6	$171.83	7.192%	$184.188	$184.19	$184.20	$184.20
Purchase #7	$130.60	9.193%	$142.6061	$142.61	$142.60	$142.60
7 purchase totals =	$1,096.38		$1,164.4147	$1,164.42	$1,164.45	$1,164.50