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	$211.88	3.427%	$219.1411	$219.14	$219.15	$219.10
Purchase #2	$149.49	12.560%	$168.2659	$168.27	$168.25	$168.30
Purchase #3	$178.30	4.442%	$186.2201	$186.22	$186.20	$186.20
Purchase #4	$54.47	12.678%	$61.3757	$61.38	$61.40	$61.40
Purchase #5	$210.96	3.837%	$219.0545	$219.05	$219.05	$219.10
Purchase #6	$178.53	10.289%	$196.899	$196.90	$196.90	$196.90
Purchase #7	$185.66	7.492%	$199.5696	$199.57	$199.55	$199.60
7 purchase totals =	$1,169.29		$1,250.5259	$1,250.53	$1,250.50	$1,250.60