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	$211.29	10.473%	$233.4184	$233.42	$233.40	$233.40
Purchase #2	$90.54	6.832%	$96.7257	$96.73	$96.75	$96.70
Purchase #3	$117.38	10.839%	$130.1028	$130.10	$130.10	$130.10
Purchase #4	$185.88	7.616%	$200.0366	$200.04	$200.05	$200.00
Purchase #5	$93.52	3.326%	$96.6305	$96.63	$96.65	$96.60
Purchase #6	$103.75	12.321%	$116.533	$116.53	$116.55	$116.50
Purchase #7	$178.93	6.744%	$190.997	$191.00	$191.00	$191.00
7 purchase totals =	$981.29		$1,064.4440	$1,064.45	$1,064.50	$1,064.30