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	$211.66	10.201%	$233.2514	$233.25	$233.25	$233.30
Purchase #2	$169.90	3.307%	$175.5186	$175.52	$175.50	$175.50
Purchase #3	$151.40	13.534%	$171.8905	$171.89	$171.90	$171.90
Purchase #4	$223.36	13.615%	$253.7705	$253.77	$253.75	$253.80
Purchase #5	$20.89	13.742%	$23.7607	$23.76	$23.75	$23.80
Purchase #6	$151.73	12.497%	$170.6917	$170.69	$170.70	$170.70
Purchase #7	$76.32	8.284%	$82.6423	$82.64	$82.65	$82.60
7 purchase totals =	$1,005.26		$1,111.5257	$1,111.52	$1,111.50	$1,111.60