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	$227.56	9.398%	$248.9461	$248.95	$248.95	$248.90
Purchase #2	$135.45	4.496%	$141.5398	$141.54	$141.55	$141.50
Purchase #3	$65.59	9.780%	$72.0047	$72.00	$72.00	$72.00
Purchase #4	$161.33	6.632%	$172.0294	$172.03	$172.05	$172.00
Purchase #5	$240.93	9.136%	$262.9414	$262.94	$262.95	$262.90
Purchase #6	$188.81	9.283%	$206.3372	$206.34	$206.35	$206.30
Purchase #7	$61.75	11.355%	$68.7617	$68.76	$68.75	$68.80
7 purchase totals =	$1,081.42		$1,172.5603	$1,172.56	$1,172.60	$1,172.40