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	$146.88	10.441%	$162.2157	$162.22	$162.20	$162.20
Purchase #2	$128.64	12.473%	$144.6853	$144.69	$144.70	$144.70
Purchase #3	$31.52	6.527%	$33.5773	$33.58	$33.60	$33.60
Purchase #4	$156.91	10.414%	$173.2506	$173.25	$173.25	$173.30
Purchase #5	$185.32	6.136%	$196.6912	$196.69	$196.70	$196.70
Purchase #6	$106.67	3.803%	$110.7267	$110.73	$110.75	$110.70
Purchase #7	$217.69	9.402%	$238.1572	$238.16	$238.15	$238.20
7 purchase totals =	$973.63		$1,059.3040	$1,059.32	$1,059.35	$1,059.40