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	$193.56	3.484%	$200.3036	$200.30	$200.30	$200.30
Purchase #2	$71.34	10.315%	$78.6987	$78.70	$78.70	$78.70
Purchase #3	$127.99	11.134%	$142.2404	$142.24	$142.25	$142.20
Purchase #4	$42.37	11.556%	$47.2663	$47.27	$47.25	$47.30
Purchase #5	$207.47	4.486%	$216.7771	$216.78	$216.80	$216.80
Purchase #6	$73.37	5.293%	$77.2535	$77.25	$77.25	$77.30
Purchase #7	$182.37	6.337%	$193.9268	$193.93	$193.95	$193.90
7 purchase totals =	$898.47		$956.4664	$956.47	$956.50	$956.50