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	$64.81	11.489%	$72.256	$72.26	$72.25	$72.30
Purchase #2	$68.36	13.184%	$77.3726	$77.37	$77.35	$77.40
Purchase #3	$83.31	13.851%	$94.8493	$94.85	$94.85	$94.80
Purchase #4	$42.96	4.426%	$44.8614	$44.86	$44.85	$44.90
Purchase #5	$113.97	11.777%	$127.3922	$127.39	$127.40	$127.40
Purchase #6	$211.83	10.219%	$233.4769	$233.48	$233.50	$233.50
Purchase #7	$244.80	12.265%	$274.8247	$274.82	$274.80	$274.80
7 purchase totals =	$830.04		$925.0331	$925.03	$925.00	$925.10