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	$219.74	9.321%	$240.222	$240.22	$240.20	$240.20
Purchase #2	$62.64	7.517%	$67.3486	$67.35	$67.35	$67.30
Purchase #3	$30.88	6.536%	$32.8983	$32.90	$32.90	$32.90
Purchase #4	$78.47	6.871%	$83.8617	$83.86	$83.85	$83.90
Purchase #5	$223.55	3.123%	$230.5315	$230.53	$230.55	$230.50
Purchase #6	$99.90	7.136%	$107.0289	$107.03	$107.05	$107.00
Purchase #7	$219.93	13.112%	$248.7672	$248.77	$248.75	$248.80
7 purchase totals =	$935.11		$1,010.6582	$1,010.66	$1,010.65	$1,010.60