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	$175.34	9.335%	$191.708	$191.71	$191.70	$191.70
Purchase #2	$9.45	9.184%	$10.3179	$10.32	$10.30	$10.30
Purchase #3	$194.97	9.198%	$212.9033	$212.90	$212.90	$212.90
Purchase #4	$175.47	6.804%	$187.409	$187.41	$187.40	$187.40
Purchase #5	$7.38	6.615%	$7.8682	$7.87	$7.85	$7.90
Purchase #6	$179.29	5.354%	$188.8892	$188.89	$188.90	$188.90
Purchase #7	$166.46	3.469%	$172.2345	$172.23	$172.25	$172.20
7 purchase totals =	$908.36		$971.3301	$971.33	$971.30	$971.30