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	$237.81	10.590%	$262.9941	$262.99	$263.00	$263.00
Purchase #2	$112.68	9.555%	$123.4466	$123.45	$123.45	$123.40
Purchase #3	$76.79	4.600%	$80.3223	$80.32	$80.30	$80.30
Purchase #4	$17.56	9.749%	$19.2719	$19.27	$19.25	$19.30
Purchase #5	$37.59	3.259%	$38.8151	$38.82	$38.80	$38.80
Purchase #6	$209.27	12.455%	$235.3346	$235.33	$235.35	$235.30
Purchase #7	$175.76	5.424%	$185.2932	$185.29	$185.30	$185.30
7 purchase totals =	$867.46		$945.4778	$945.47	$945.45	$945.40