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	$221.89	8.552%	$240.866	$240.87	$240.85	$240.90
Purchase #2	$20.89	3.327%	$21.585	$21.59	$21.60	$21.60
Purchase #3	$196.96	6.801%	$210.3552	$210.36	$210.35	$210.40
Purchase #4	$26.87	4.440%	$28.063	$28.06	$28.05	$28.10
Purchase #5	$206.70	3.543%	$214.0234	$214.02	$214.00	$214.00
Purchase #6	$52.97	12.729%	$59.7126	$59.71	$59.70	$59.70
Purchase #7	$240.80	12.513%	$270.9313	$270.93	$270.95	$270.90
7 purchase totals =	$967.08		$1,045.5365	$1,045.54	$1,045.50	$1,045.60