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	$217.49	7.442%	$233.6756	$233.68	$233.70	$233.70
Purchase #2	$201.33	7.258%	$215.9425	$215.94	$215.95	$215.90
Purchase #3	$210.47	8.755%	$228.8966	$228.90	$228.90	$228.90
Purchase #4	$151.90	8.410%	$164.6748	$164.67	$164.65	$164.70
Purchase #5	$83.43	7.769%	$89.9117	$89.91	$89.90	$89.90
Purchase #6	$74.36	5.505%	$78.4535	$78.45	$78.45	$78.50
Purchase #7	$47.85	6.553%	$50.9856	$50.99	$51.00	$51.00
7 purchase totals =	$986.83		$1,062.5403	$1,062.54	$1,062.55	$1,062.60