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	$185.84	5.316%	$195.7193	$195.72	$195.70	$195.70
Purchase #2	$48.70	3.478%	$50.3938	$50.39	$50.40	$50.40
Purchase #3	$214.89	3.357%	$222.1039	$222.10	$222.10	$222.10
Purchase #4	$25.84	8.292%	$27.9827	$27.98	$28.00	$28.00
Purchase #5	$200.73	11.268%	$223.3483	$223.35	$223.35	$223.30
Purchase #6	$56.86	5.281%	$59.8628	$59.86	$59.85	$59.90
Purchase #7	$155.67	9.768%	$170.8758	$170.88	$170.90	$170.90
7 purchase totals =	$888.53		$950.2866	$950.28	$950.30	$950.30