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	$145.91	4.184%	$152.0149	$152.01	$152.00	$152.00
Purchase #2	$53.42	10.807%	$59.1931	$59.19	$59.20	$59.20
Purchase #3	$201.70	10.172%	$222.2169	$222.22	$222.20	$222.20
Purchase #4	$147.50	11.664%	$164.7044	$164.70	$164.70	$164.70
Purchase #5	$201.82	10.466%	$222.9425	$222.94	$222.95	$222.90
Purchase #6	$66.27	9.847%	$72.7956	$72.80	$72.80	$72.80
Purchase #7	$166.84	5.178%	$175.479	$175.48	$175.50	$175.50
7 purchase totals =	$983.46		$1,069.3464	$1,069.34	$1,069.35	$1,069.30