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	$152.37	7.120%	$163.2187	$163.22	$163.20	$163.20
Purchase #2	$41.35	5.439%	$43.599	$43.60	$43.60	$43.60
Purchase #3	$210.77	3.380%	$217.894	$217.89	$217.90	$217.90
Purchase #4	$134.58	5.610%	$142.1299	$142.13	$142.15	$142.10
Purchase #5	$200.33	9.615%	$219.5917	$219.59	$219.60	$219.60
Purchase #6	$250.64	6.643%	$267.29	$267.29	$267.30	$267.30
Purchase #7	$54.42	9.748%	$59.7249	$59.72	$59.70	$59.70
7 purchase totals =	$1,044.46		$1,113.4482	$1,113.44	$1,113.45	$1,113.40