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	$188.78	12.289%	$211.9792	$211.98	$212.00	$212.00
Purchase #2	$67.96	5.337%	$71.587	$71.59	$71.60	$71.60
Purchase #3	$155.70	12.789%	$175.6125	$175.61	$175.60	$175.60
Purchase #4	$205.70	5.693%	$217.4105	$217.41	$217.40	$217.40
Purchase #5	$41.49	12.670%	$46.7468	$46.75	$46.75	$46.70
Purchase #6	$150.98	11.515%	$168.3653	$168.37	$168.35	$168.40
Purchase #7	$207.60	5.803%	$219.647	$219.65	$219.65	$219.60
7 purchase totals =	$1,018.21		$1,111.3483	$1,111.36	$1,111.35	$1,111.30