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	$127.92	5.122%	$134.4721	$134.47	$134.45	$134.50
Purchase #2	$243.43	3.305%	$251.4754	$251.48	$251.50	$251.50
Purchase #3	$221.49	7.479%	$238.0552	$238.06	$238.05	$238.10
Purchase #4	$243.76	3.802%	$253.0278	$253.03	$253.05	$253.00
Purchase #5	$200.59	12.492%	$225.6477	$225.65	$225.65	$225.60
Purchase #6	$84.96	5.433%	$89.5759	$89.58	$89.60	$89.60
Purchase #7	$231.83	5.492%	$244.5621	$244.56	$244.55	$244.60
7 purchase totals =	$1,353.98		$1,436.8162	$1,436.83	$1,436.85	$1,436.90