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	$135.72	11.754%	$151.6725	$151.67	$151.65	$151.70
Purchase #2	$55.29	8.228%	$59.8393	$59.84	$59.85	$59.80
Purchase #3	$164.75	12.366%	$185.123	$185.12	$185.10	$185.10
Purchase #4	$156.98	12.418%	$176.4738	$176.47	$176.45	$176.50
Purchase #5	$202.57	3.846%	$210.3608	$210.36	$210.35	$210.40
Purchase #6	$60.37	7.633%	$64.978	$64.98	$65.00	$65.00
Purchase #7	$173.30	7.706%	$186.6545	$186.65	$186.65	$186.70
7 purchase totals =	$948.98		$1,035.1019	$1,035.09	$1,035.05	$1,035.20