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	$209.40	3.574%	$216.884	$216.88	$216.90	$216.90
Purchase #2	$31.45	6.676%	$33.5496	$33.55	$33.55	$33.50
Purchase #3	$49.74	5.124%	$52.2887	$52.29	$52.30	$52.30
Purchase #4	$168.98	5.858%	$178.8788	$178.88	$178.90	$178.90
Purchase #5	$241.65	6.314%	$256.9078	$256.91	$256.90	$256.90
Purchase #6	$194.29	9.170%	$212.1064	$212.11	$212.10	$212.10
Purchase #7	$123.93	7.197%	$132.8492	$132.85	$132.85	$132.80
7 purchase totals =	$1,019.44		$1,083.4645	$1,083.47	$1,083.50	$1,083.40