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	$98.37	7.835%	$106.0773	$106.08	$106.10	$106.10
Purchase #2	$243.77	7.642%	$262.3989	$262.40	$262.40	$262.40
Purchase #3	$80.92	12.286%	$90.8618	$90.86	$90.85	$90.90
Purchase #4	$43.81	12.779%	$49.4085	$49.41	$49.40	$49.40
Purchase #5	$111.32	11.522%	$124.1463	$124.15	$124.15	$124.10
Purchase #6	$100.33	6.625%	$106.9769	$106.98	$107.00	$107.00
Purchase #7	$240.81	13.295%	$272.8257	$272.83	$272.85	$272.80
7 purchase totals =	$919.33		$1,012.6954	$1,012.71	$1,012.75	$1,012.70