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	$43.95	11.495%	$49.0021	$49.00	$49.00	$49.00
Purchase #2	$175.90	5.529%	$185.6255	$185.63	$185.65	$185.60
Purchase #3	$86.27	10.249%	$95.1118	$95.11	$95.10	$95.10
Purchase #4	$184.78	11.584%	$206.1849	$206.18	$206.20	$206.20
Purchase #5	$181.43	8.129%	$196.1784	$196.18	$196.20	$196.20
Purchase #6	$167.82	8.758%	$182.5177	$182.52	$182.50	$182.50
Purchase #7	$50.86	5.410%	$53.6115	$53.61	$53.60	$53.60
7 purchase totals =	$891.01		$968.2319	$968.23	$968.25	$968.20