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	$65.34	11.645%	$72.9488	$72.95	$72.95	$72.90
Purchase #2	$188.65	11.726%	$210.7711	$210.77	$210.75	$210.80
Purchase #3	$109.72	13.431%	$124.4565	$124.46	$124.45	$124.50
Purchase #4	$186.93	6.371%	$198.8393	$198.84	$198.85	$198.80
Purchase #5	$157.75	9.164%	$172.2062	$172.21	$172.20	$172.20
Purchase #6	$103.63	12.196%	$116.2687	$116.27	$116.25	$116.30
Purchase #7	$205.26	6.183%	$217.9512	$217.95	$217.95	$218.00
7 purchase totals =	$1,017.28		$1,113.4418	$1,113.45	$1,113.40	$1,113.50