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	$82.38	4.362%	$85.9734	$85.97	$85.95	$86.00
Purchase #2	$48.86	8.209%	$52.8709	$52.87	$52.85	$52.90
Purchase #3	$85.31	3.609%	$88.3888	$88.39	$88.40	$88.40
Purchase #4	$169.42	5.221%	$178.2654	$178.27	$178.25	$178.30
Purchase #5	$23.47	10.561%	$25.9487	$25.95	$25.95	$25.90
Purchase #6	$159.87	7.787%	$172.3191	$172.32	$172.30	$172.30
Purchase #7	$213.49	5.524%	$225.2832	$225.28	$225.30	$225.30
7 purchase totals =	$782.80		$829.0495	$829.05	$829.00	$829.10