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	$104.89	6.733%	$111.9522	$111.95	$111.95	$112.00
Purchase #2	$167.48	8.836%	$182.2785	$182.28	$182.30	$182.30
Purchase #3	$75.37	7.181%	$80.7823	$80.78	$80.80	$80.80
Purchase #4	$187.65	4.539%	$196.1674	$196.17	$196.15	$196.20
Purchase #5	$104.31	11.597%	$116.4068	$116.41	$116.40	$116.40
Purchase #6	$181.48	5.151%	$190.828	$190.83	$190.85	$190.80
Purchase #7	$172.98	5.428%	$182.3694	$182.37	$182.35	$182.40
7 purchase totals =	$994.16		$1,060.7846	$1,060.79	$1,060.80	$1,060.90