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	$80.71	6.503%	$85.9586	$85.96	$85.95	$86.00
Purchase #2	$162.88	8.355%	$176.4886	$176.49	$176.50	$176.50
Purchase #3	$190.92	7.447%	$205.1378	$205.14	$205.15	$205.10
Purchase #4	$29.87	8.737%	$32.4797	$32.48	$32.50	$32.50
Purchase #5	$245.93	6.697%	$262.3999	$262.40	$262.40	$262.40
Purchase #6	$173.41	7.703%	$186.7678	$186.77	$186.75	$186.80
Purchase #7	$57.28	3.554%	$59.3157	$59.32	$59.30	$59.30
7 purchase totals =	$941.00		$1,008.5481	$1,008.56	$1,008.55	$1,008.60