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	$85.82	9.495%	$93.9686	$93.97	$93.95	$94.00
Purchase #2	$52.51	13.371%	$59.5311	$59.53	$59.55	$59.50
Purchase #3	$186.55	8.251%	$201.9422	$201.94	$201.95	$201.90
Purchase #4	$157.33	6.433%	$167.451	$167.45	$167.45	$167.50
Purchase #5	$213.91	6.302%	$227.3906	$227.39	$227.40	$227.40
Purchase #6	$139.38	4.601%	$145.7929	$145.79	$145.80	$145.80
Purchase #7	$176.25	11.371%	$196.2914	$196.29	$196.30	$196.30
7 purchase totals =	$1,011.75		$1,092.3678	$1,092.36	$1,092.40	$1,092.40