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	$9.69	7.759%	$10.4418	$10.44	$10.45	$10.40
Purchase #2	$170.43	6.141%	$180.8961	$180.90	$180.90	$180.90
Purchase #3	$127.59	5.515%	$134.6266	$134.63	$134.65	$134.60
Purchase #4	$240.88	10.283%	$265.6497	$265.65	$265.65	$265.60
Purchase #5	$154.43	3.623%	$160.025	$160.03	$160.05	$160.00
Purchase #6	$62.69	8.339%	$67.9177	$67.92	$67.90	$67.90
Purchase #7	$218.98	10.376%	$241.7014	$241.70	$241.70	$241.70
7 purchase totals =	$984.69		$1,061.2583	$1,061.27	$1,061.30	$1,061.10