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	$153.60	7.669%	$165.3796	$165.38	$165.40	$165.40
Purchase #2	$67.62	6.800%	$72.2182	$72.22	$72.20	$72.20
Purchase #3	$67.25	4.669%	$70.3899	$70.39	$70.40	$70.40
Purchase #4	$194.62	11.289%	$216.5907	$216.59	$216.60	$216.60
Purchase #5	$78.34	5.108%	$82.3416	$82.34	$82.35	$82.30
Purchase #6	$233.96	3.207%	$241.4631	$241.46	$241.45	$241.50
Purchase #7	$157.34	10.276%	$173.5083	$173.51	$173.50	$173.50
7 purchase totals =	$952.73		$1,021.8914	$1,021.89	$1,021.90	$1,021.90