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	$176.58	5.275%	$185.8946	$185.89	$185.90	$185.90
Purchase #2	$173.48	3.377%	$179.3384	$179.34	$179.35	$179.30
Purchase #3	$5.82	6.280%	$6.1855	$6.19	$6.20	$6.20
Purchase #4	$24.85	10.567%	$27.4759	$27.48	$27.50	$27.50
Purchase #5	$238.38	10.857%	$264.2609	$264.26	$264.25	$264.30
Purchase #6	$178.55	8.161%	$193.1215	$193.12	$193.10	$193.10
Purchase #7	$173.78	6.474%	$185.0305	$185.03	$185.05	$185.00
7 purchase totals =	$971.44		$1,041.3073	$1,041.31	$1,041.35	$1,041.30