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	$126.43	8.403%	$137.0539	$137.05	$137.05	$137.10
Purchase #2	$169.41	12.620%	$190.7895	$190.79	$190.80	$190.80
Purchase #3	$31.48	7.690%	$33.9008	$33.90	$33.90	$33.90
Purchase #4	$62.32	4.476%	$65.1094	$65.11	$65.10	$65.10
Purchase #5	$128.73	5.164%	$135.3776	$135.38	$135.40	$135.40
Purchase #6	$216.69	5.539%	$228.6925	$228.69	$228.70	$228.70
Purchase #7	$218.47	3.238%	$225.5441	$225.54	$225.55	$225.50
7 purchase totals =	$953.53		$1,016.4678	$1,016.46	$1,016.50	$1,016.50