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	$78.61	11.398%	$87.57	$87.57	$87.55	$87.60
Purchase #2	$144.61	10.235%	$159.4108	$159.41	$159.40	$159.40
Purchase #3	$179.81	10.132%	$198.0283	$198.03	$198.05	$198.00
Purchase #4	$131.46	4.197%	$136.9774	$136.98	$137.00	$137.00
Purchase #5	$92.59	13.398%	$104.9952	$105.00	$105.00	$105.00
Purchase #6	$240.56	5.814%	$254.5462	$254.55	$254.55	$254.50
Purchase #7	$56.74	11.176%	$63.0813	$63.08	$63.10	$63.10
7 purchase totals =	$924.38		$1,004.6092	$1,004.62	$1,004.65	$1,004.60