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	$100.58	4.437%	$105.0427	$105.04	$105.05	$105.00
Purchase #2	$212.50	5.145%	$223.4331	$223.43	$223.45	$223.40
Purchase #3	$173.50	8.796%	$188.7611	$188.76	$188.75	$188.80
Purchase #4	$213.72	5.317%	$225.0835	$225.08	$225.10	$225.10
Purchase #5	$39.45	8.574%	$42.8324	$42.83	$42.85	$42.80
Purchase #6	$67.68	6.805%	$72.2856	$72.29	$72.30	$72.30
Purchase #7	$203.87	5.751%	$215.5946	$215.59	$215.60	$215.60
7 purchase totals =	$1,011.30		$1,073.0330	$1,073.02	$1,073.10	$1,073.00