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	$89.43	5.707%	$94.5338	$94.53	$94.55	$94.50
Purchase #2	$11.90	5.814%	$12.5919	$12.59	$12.60	$12.60
Purchase #3	$147.59	10.366%	$162.8892	$162.89	$162.90	$162.90
Purchase #4	$168.56	3.347%	$174.2017	$174.20	$174.20	$174.20
Purchase #5	$215.79	9.212%	$235.6686	$235.67	$235.65	$235.70
Purchase #6	$59.55	13.575%	$67.6339	$67.63	$67.65	$67.60
Purchase #7	$211.41	4.772%	$221.4985	$221.50	$221.50	$221.50
7 purchase totals =	$904.23		$969.0176	$969.01	$969.05	$969.00