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	$181.78	8.739%	$197.6658	$197.67	$197.65	$197.70
Purchase #2	$177.45	4.285%	$185.0537	$185.05	$185.05	$185.10
Purchase #3	$176.36	11.237%	$196.1776	$196.18	$196.20	$196.20
Purchase #4	$117.85	6.604%	$125.6328	$125.63	$125.65	$125.60
Purchase #5	$85.34	4.315%	$89.0224	$89.02	$89.00	$89.00
Purchase #6	$136.59	3.734%	$141.6903	$141.69	$141.70	$141.70
Purchase #7	$127.67	9.740%	$140.1051	$140.11	$140.10	$140.10
7 purchase totals =	$1,003.04		$1,075.3477	$1,075.35	$1,075.35	$1,075.40