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	$169.59	7.413%	$182.1617	$182.16	$182.15	$182.20
Purchase #2	$99.27	4.127%	$103.3669	$103.37	$103.35	$103.40
Purchase #3	$126.45	6.315%	$134.4353	$134.44	$134.45	$134.40
Purchase #4	$150.94	9.243%	$164.8914	$164.89	$164.90	$164.90
Purchase #5	$111.27	13.550%	$126.3471	$126.35	$126.35	$126.30
Purchase #6	$127.57	9.513%	$139.7057	$139.71	$139.70	$139.70
Purchase #7	$144.86	7.789%	$156.1431	$156.14	$156.15	$156.10
7 purchase totals =	$929.95		$1,007.0512	$1,007.06	$1,007.05	$1,007.00