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	$189.30	3.757%	$196.412	$196.41	$196.40	$196.40
Purchase #2	$170.25	6.218%	$180.8361	$180.84	$180.85	$180.80
Purchase #3	$164.38	4.189%	$171.2659	$171.27	$171.25	$171.30
Purchase #4	$92.75	12.115%	$103.9867	$103.99	$104.00	$104.00
Purchase #5	$59.31	9.206%	$64.7701	$64.77	$64.75	$64.80
Purchase #6	$132.71	11.870%	$148.4627	$148.46	$148.45	$148.50
Purchase #7	$167.52	11.363%	$186.5553	$186.56	$186.55	$186.60
7 purchase totals =	$976.22		$1,052.2888	$1,052.30	$1,052.25	$1,052.40