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	$182.57	4.801%	$191.3352	$191.34	$191.35	$191.30
Purchase #2	$11.38	7.449%	$12.2277	$12.23	$12.25	$12.20
Purchase #3	$77.32	8.615%	$83.9811	$83.98	$84.00	$84.00
Purchase #4	$130.27	5.283%	$137.1522	$137.15	$137.15	$137.20
Purchase #5	$150.30	10.383%	$165.9056	$165.91	$165.90	$165.90
Purchase #6	$93.46	12.848%	$105.4677	$105.47	$105.45	$105.50
Purchase #7	$178.80	10.137%	$196.925	$196.93	$196.95	$196.90
7 purchase totals =	$824.10		$892.9945	$893.01	$893.05	$893.00