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	$56.32	9.189%	$61.4952	$61.50	$61.50	$61.50
Purchase #2	$19.57	4.815%	$20.5123	$20.51	$20.50	$20.50
Purchase #3	$68.55	4.732%	$71.7938	$71.79	$71.80	$71.80
Purchase #4	$245.74	6.792%	$262.4307	$262.43	$262.45	$262.40
Purchase #5	$225.88	3.320%	$233.3792	$233.38	$233.40	$233.40
Purchase #6	$224.48	11.442%	$250.165	$250.17	$250.15	$250.20
Purchase #7	$105.71	5.429%	$111.449	$111.45	$111.45	$111.40
7 purchase totals =	$946.25		$1,011.2252	$1,011.23	$1,011.25	$1,011.20