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	$221.82	10.644%	$245.4305	$245.43	$245.45	$245.40
Purchase #2	$69.97	6.486%	$74.5083	$74.51	$74.50	$74.50
Purchase #3	$222.67	13.680%	$253.1313	$253.13	$253.15	$253.10
Purchase #4	$166.65	7.708%	$179.4954	$179.50	$179.50	$179.50
Purchase #5	$63.38	7.108%	$67.8851	$67.89	$67.90	$67.90
Purchase #6	$14.94	5.869%	$15.8168	$15.82	$15.80	$15.80
Purchase #7	$208.90	3.353%	$215.9044	$215.90	$215.90	$215.90
7 purchase totals =	$968.33		$1,052.1718	$1,052.18	$1,052.20	$1,052.10