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	$38.99	12.745%	$43.9593	$43.96	$43.95	$44.00
Purchase #2	$126.61	7.139%	$135.6487	$135.65	$135.65	$135.60
Purchase #3	$127.43	13.321%	$144.405	$144.41	$144.40	$144.40
Purchase #4	$240.95	6.466%	$256.5298	$256.53	$256.55	$256.50
Purchase #5	$184.26	3.386%	$190.499	$190.50	$190.50	$190.50
Purchase #6	$137.42	10.648%	$152.0525	$152.05	$152.05	$152.10
Purchase #7	$163.66	4.500%	$171.0247	$171.02	$171.00	$171.00
7 purchase totals =	$1,019.32		$1,094.1190	$1,094.12	$1,094.10	$1,094.10