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	$181.48	8.275%	$196.4975	$196.50	$196.50	$196.50
Purchase #2	$125.53	9.128%	$136.9884	$136.99	$137.00	$137.00
Purchase #3	$84.27	7.846%	$90.8818	$90.88	$90.90	$90.90
Purchase #4	$154.91	9.326%	$169.3569	$169.36	$169.35	$169.40
Purchase #5	$110.55	3.318%	$114.218	$114.22	$114.20	$114.20
Purchase #6	$105.94	5.567%	$111.8377	$111.84	$111.85	$111.80
Purchase #7	$197.50	11.695%	$220.5976	$220.60	$220.60	$220.60
7 purchase totals =	$960.18		$1,040.3779	$1,040.39	$1,040.40	$1,040.40