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	$58.30	5.780%	$61.6697	$61.67	$61.65	$61.70
Purchase #2	$225.86	6.193%	$239.8475	$239.85	$239.85	$239.80
Purchase #3	$97.41	12.635%	$109.7178	$109.72	$109.70	$109.70
Purchase #4	$216.73	5.582%	$228.8279	$228.83	$228.85	$228.80
Purchase #5	$64.63	12.343%	$72.6073	$72.61	$72.60	$72.60
Purchase #6	$84.74	7.702%	$91.2667	$91.27	$91.25	$91.30
Purchase #7	$105.47	4.384%	$110.0938	$110.09	$110.10	$110.10
7 purchase totals =	$853.14		$914.0307	$914.04	$914.00	$914.00