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	$218.32	11.787%	$244.0534	$244.05	$244.05	$244.10
Purchase #2	$52.61	8.549%	$57.1076	$57.11	$57.10	$57.10
Purchase #3	$84.50	8.108%	$91.3513	$91.35	$91.35	$91.40
Purchase #4	$47.47	6.281%	$50.4516	$50.45	$50.45	$50.50
Purchase #5	$16.64	11.477%	$18.5498	$18.55	$18.55	$18.50
Purchase #6	$62.59	8.447%	$67.877	$67.88	$67.90	$67.90
Purchase #7	$80.59	5.597%	$85.1006	$85.10	$85.10	$85.10
7 purchase totals =	$562.72		$614.4913	$614.49	$614.50	$614.60