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	$104.63	5.293%	$110.1681	$110.17	$110.15	$110.20
Purchase #2	$187.27	6.443%	$199.3358	$199.34	$199.35	$199.30
Purchase #3	$35.56	5.292%	$37.4418	$37.44	$37.45	$37.40
Purchase #4	$193.94	12.139%	$217.4824	$217.48	$217.50	$217.50
Purchase #5	$28.59	13.703%	$32.5077	$32.51	$32.50	$32.50
Purchase #6	$238.74	9.125%	$260.525	$260.53	$260.55	$260.50
Purchase #7	$180.69	3.783%	$187.5255	$187.53	$187.55	$187.50
7 purchase totals =	$969.42		$1,044.9863	$1,045.00	$1,045.05	$1,044.90