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	$216.70	4.294%	$226.0051	$226.01	$226.00	$226.00
Purchase #2	$156.89	6.199%	$166.6156	$166.62	$166.60	$166.60
Purchase #3	$125.98	10.209%	$138.8413	$138.84	$138.85	$138.80
Purchase #4	$243.27	3.455%	$251.675	$251.68	$251.70	$251.70
Purchase #5	$119.27	12.738%	$134.4626	$134.46	$134.45	$134.50
Purchase #6	$173.94	13.213%	$196.9227	$196.92	$196.90	$196.90
Purchase #7	$77.88	5.438%	$82.1151	$82.12	$82.10	$82.10
7 purchase totals =	$1,113.93		$1,196.6374	$1,196.65	$1,196.60	$1,196.60