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	$93.65	5.680%	$98.9693	$98.97	$98.95	$99.00
Purchase #2	$245.71	6.132%	$260.7769	$260.78	$260.80	$260.80
Purchase #3	$54.54	11.661%	$60.8999	$60.90	$60.90	$60.90
Purchase #4	$130.90	4.367%	$136.6164	$136.62	$136.60	$136.60
Purchase #5	$148.96	10.358%	$164.3893	$164.39	$164.40	$164.40
Purchase #6	$147.34	5.563%	$155.5365	$155.54	$155.55	$155.50
Purchase #7	$209.79	4.227%	$218.6578	$218.66	$218.65	$218.70
7 purchase totals =	$1,030.89		$1,095.8461	$1,095.86	$1,095.85	$1,095.90