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	$214.96	5.729%	$227.2751	$227.28	$227.30	$227.30
Purchase #2	$82.88	5.815%	$87.6995	$87.70	$87.70	$87.70
Purchase #3	$64.71	12.649%	$72.8952	$72.90	$72.90	$72.90
Purchase #4	$171.31	5.145%	$180.1239	$180.12	$180.10	$180.10
Purchase #5	$88.79	11.707%	$99.1846	$99.18	$99.20	$99.20
Purchase #6	$148.65	13.483%	$168.6925	$168.69	$168.70	$168.70
Purchase #7	$205.71	4.552%	$215.0739	$215.07	$215.05	$215.10
7 purchase totals =	$977.01		$1,050.9447	$1,050.94	$1,050.95	$1,051.00