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	$197.68	8.174%	$213.8384	$213.84	$213.85	$213.80
Purchase #2	$186.40	5.364%	$196.3985	$196.40	$196.40	$196.40
Purchase #3	$181.31	13.555%	$205.8866	$205.89	$205.90	$205.90
Purchase #4	$98.91	6.673%	$105.5103	$105.51	$105.50	$105.50
Purchase #5	$153.43	5.601%	$162.0236	$162.02	$162.00	$162.00
Purchase #6	$95.43	3.220%	$98.5028	$98.50	$98.50	$98.50
Purchase #7	$94.87	5.625%	$100.2064	$100.21	$100.20	$100.20
7 purchase totals =	$1,008.03		$1,082.3666	$1,082.37	$1,082.35	$1,082.30