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	$103.40	5.863%	$109.4623	$109.46	$109.45	$109.50
Purchase #2	$154.77	5.662%	$163.5331	$163.53	$163.55	$163.50
Purchase #3	$191.61	5.112%	$201.4051	$201.41	$201.40	$201.40
Purchase #4	$50.33	11.461%	$56.0983	$56.10	$56.10	$56.10
Purchase #5	$196.41	13.602%	$223.1257	$223.13	$223.15	$223.10
Purchase #6	$54.93	11.259%	$61.1146	$61.11	$61.10	$61.10
Purchase #7	$63.68	13.563%	$72.3169	$72.32	$72.30	$72.30
7 purchase totals =	$815.13		$887.0560	$887.06	$887.05	$887.00