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	$193.90	7.402%	$208.2525	$208.25	$208.25	$208.30
Purchase #2	$176.39	11.264%	$196.2586	$196.26	$196.25	$196.30
Purchase #3	$147.57	13.845%	$168.0011	$168.00	$168.00	$168.00
Purchase #4	$24.91	11.162%	$27.6905	$27.69	$27.70	$27.70
Purchase #5	$41.36	3.212%	$42.6885	$42.69	$42.70	$42.70
Purchase #6	$216.80	10.425%	$239.4014	$239.40	$239.40	$239.40
Purchase #7	$202.41	7.405%	$217.3985	$217.40	$217.40	$217.40
7 purchase totals =	$1,003.34		$1,099.6911	$1,099.69	$1,099.70	$1,099.80