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	$223.48	5.166%	$235.025	$235.03	$235.05	$235.00
Purchase #2	$46.73	12.365%	$52.5082	$52.51	$52.50	$52.50
Purchase #3	$157.89	5.609%	$166.7461	$166.75	$166.75	$166.70
Purchase #4	$176.45	5.187%	$185.6025	$185.60	$185.60	$185.60
Purchase #5	$23.51	13.650%	$26.7191	$26.72	$26.70	$26.70
Purchase #6	$181.41	13.776%	$206.401	$206.40	$206.40	$206.40
Purchase #7	$152.90	3.722%	$158.5909	$158.59	$158.60	$158.60
7 purchase totals =	$962.37		$1,031.5928	$1,031.60	$1,031.60	$1,031.50