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	$182.62	13.791%	$207.8051	$207.81	$207.80	$207.80
Purchase #2	$47.66	6.648%	$50.8284	$50.83	$50.85	$50.80
Purchase #3	$61.32	10.535%	$67.7801	$67.78	$67.80	$67.80
Purchase #4	$114.31	8.460%	$123.9806	$123.98	$124.00	$124.00
Purchase #5	$140.26	12.841%	$158.2708	$158.27	$158.25	$158.30
Purchase #6	$240.77	7.533%	$258.9072	$258.91	$258.90	$258.90
Purchase #7	$168.80	6.211%	$179.2842	$179.28	$179.30	$179.30
7 purchase totals =	$955.74		$1,046.8564	$1,046.86	$1,046.90	$1,046.90