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	$226.61	6.322%	$240.9363	$240.94	$240.95	$240.90
Purchase #2	$186.83	5.379%	$196.8796	$196.88	$196.90	$196.90
Purchase #3	$205.53	4.612%	$215.009	$215.01	$215.00	$215.00
Purchase #4	$79.46	12.287%	$89.2233	$89.22	$89.20	$89.20
Purchase #5	$61.73	10.771%	$68.3789	$68.38	$68.40	$68.40
Purchase #6	$156.26	3.107%	$161.115	$161.12	$161.10	$161.10
Purchase #7	$115.26	7.259%	$123.6267	$123.63	$123.65	$123.60
7 purchase totals =	$1,031.68		$1,095.1688	$1,095.18	$1,095.20	$1,095.10