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	$225.58	11.130%	$250.6871	$250.69	$250.70	$250.70
Purchase #2	$48.50	11.233%	$53.948	$53.95	$53.95	$53.90
Purchase #3	$110.56	6.307%	$117.533	$117.53	$117.55	$117.50
Purchase #4	$201.97	6.700%	$215.502	$215.50	$215.50	$215.50
Purchase #5	$72.55	7.177%	$77.7569	$77.76	$77.75	$77.80
Purchase #6	$92.35	7.810%	$99.5625	$99.56	$99.55	$99.60
Purchase #7	$228.49	9.158%	$249.4151	$249.42	$249.40	$249.40
7 purchase totals =	$980.00		$1,064.4046	$1,064.41	$1,064.40	$1,064.40