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	$190.41	9.718%	$208.914	$208.91	$208.90	$208.90
Purchase #2	$142.83	7.761%	$153.915	$153.92	$153.90	$153.90
Purchase #3	$199.64	4.870%	$209.3625	$209.36	$209.35	$209.40
Purchase #4	$240.73	8.617%	$261.4737	$261.47	$261.45	$261.50
Purchase #5	$90.41	3.420%	$93.502	$93.50	$93.50	$93.50
Purchase #6	$221.96	3.159%	$228.9717	$228.97	$228.95	$229.00
Purchase #7	$131.77	9.529%	$144.3264	$144.33	$144.35	$144.30
7 purchase totals =	$1,217.75		$1,300.4653	$1,300.46	$1,300.40	$1,300.50