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	$40.40	9.761%	$44.3434	$44.34	$44.35	$44.30
Purchase #2	$190.59	3.213%	$196.7137	$196.71	$196.70	$196.70
Purchase #3	$88.36	6.691%	$94.2722	$94.27	$94.25	$94.30
Purchase #4	$157.31	7.659%	$169.3584	$169.36	$169.35	$169.40
Purchase #5	$197.82	9.151%	$215.9225	$215.92	$215.90	$215.90
Purchase #6	$165.72	13.844%	$188.6623	$188.66	$188.65	$188.70
Purchase #7	$237.87	10.618%	$263.127	$263.13	$263.15	$263.10
7 purchase totals =	$1,078.07		$1,172.3995	$1,172.39	$1,172.35	$1,172.40