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	$194.59	3.206%	$200.8286	$200.83	$200.85	$200.80
Purchase #2	$118.76	8.395%	$128.7299	$128.73	$128.75	$128.70
Purchase #3	$200.62	5.851%	$212.3583	$212.36	$212.35	$212.40
Purchase #4	$187.48	11.135%	$208.3559	$208.36	$208.35	$208.40
Purchase #5	$99.26	3.275%	$102.5108	$102.51	$102.50	$102.50
Purchase #6	$18.69	8.577%	$20.293	$20.29	$20.30	$20.30
Purchase #7	$184.44	3.247%	$190.4288	$190.43	$190.45	$190.40
7 purchase totals =	$1,003.84		$1,063.5053	$1,063.51	$1,063.55	$1,063.50