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	$177.34	10.809%	$196.5087	$196.51	$196.50	$196.50
Purchase #2	$22.46	7.155%	$24.067	$24.07	$24.05	$24.10
Purchase #3	$234.89	11.609%	$262.1584	$262.16	$262.15	$262.20
Purchase #4	$136.64	10.614%	$151.143	$151.14	$151.15	$151.10
Purchase #5	$92.97	4.548%	$97.1983	$97.20	$97.20	$97.20
Purchase #6	$73.89	7.514%	$79.4421	$79.44	$79.45	$79.40
Purchase #7	$209.54	4.215%	$218.3721	$218.37	$218.35	$218.40
7 purchase totals =	$947.73		$1,028.8896	$1,028.89	$1,028.85	$1,028.90