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	$222.33	6.535%	$236.8593	$236.86	$236.85	$236.90
Purchase #2	$31.28	7.578%	$33.6504	$33.65	$33.65	$33.70
Purchase #3	$94.60	10.718%	$104.7392	$104.74	$104.75	$104.70
Purchase #4	$42.76	5.424%	$45.0793	$45.08	$45.10	$45.10
Purchase #5	$189.96	3.669%	$196.9296	$196.93	$196.95	$196.90
Purchase #6	$85.29	13.323%	$96.6532	$96.65	$96.65	$96.70
Purchase #7	$44.60	7.654%	$48.0137	$48.01	$48.00	$48.00
7 purchase totals =	$710.82		$761.9247	$761.92	$761.95	$762.00