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	$228.72	3.481%	$236.6817	$236.68	$236.70	$236.70
Purchase #2	$196.38	5.367%	$206.9197	$206.92	$206.90	$206.90
Purchase #3	$37.80	12.329%	$42.4604	$42.46	$42.45	$42.50
Purchase #4	$231.44	13.745%	$263.2514	$263.25	$263.25	$263.30
Purchase #5	$59.88	5.113%	$62.9417	$62.94	$62.95	$62.90
Purchase #6	$18.37	10.349%	$20.2711	$20.27	$20.25	$20.30
Purchase #7	$160.67	11.635%	$179.364	$179.36	$179.35	$179.40
7 purchase totals =	$933.26		$1,011.8900	$1,011.88	$1,011.85	$1,012.00