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	$167.96	4.255%	$175.1067	$175.11	$175.10	$175.10
Purchase #2	$141.78	9.562%	$155.337	$155.34	$155.35	$155.30
Purchase #3	$11.48	9.378%	$12.5566	$12.56	$12.55	$12.60
Purchase #4	$189.44	3.518%	$196.1045	$196.10	$196.10	$196.10
Purchase #5	$171.43	9.207%	$187.2136	$187.21	$187.20	$187.20
Purchase #6	$143.60	10.366%	$158.4856	$158.49	$158.50	$158.50
Purchase #7	$130.86	5.401%	$137.9277	$137.93	$137.95	$137.90
7 purchase totals =	$956.55		$1,022.7317	$1,022.74	$1,022.75	$1,022.70