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	$206.25	4.400%	$215.325	$215.33	$215.35	$215.30
Purchase #2	$205.63	11.511%	$229.3001	$229.30	$229.30	$229.30
Purchase #3	$22.87	12.228%	$25.6665	$25.67	$25.65	$25.70
Purchase #4	$92.52	5.506%	$97.6142	$97.61	$97.60	$97.60
Purchase #5	$117.64	4.715%	$123.1867	$123.19	$123.20	$123.20
Purchase #6	$93.32	10.665%	$103.2726	$103.27	$103.25	$103.30
Purchase #7	$205.98	4.464%	$215.1749	$215.17	$215.15	$215.20
7 purchase totals =	$944.21		$1,009.5400	$1,009.54	$1,009.50	$1,009.60