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	$119.38	5.446%	$125.8814	$125.88	$125.90	$125.90
Purchase #2	$218.59	13.272%	$247.6013	$247.60	$247.60	$247.60
Purchase #3	$144.90	13.812%	$164.9136	$164.91	$164.90	$164.90
Purchase #4	$59.73	13.155%	$67.5875	$67.59	$67.60	$67.60
Purchase #5	$86.90	12.562%	$97.8164	$97.82	$97.80	$97.80
Purchase #6	$186.25	4.302%	$194.2625	$194.26	$194.25	$194.30
Purchase #7	$165.69	8.486%	$179.7505	$179.75	$179.75	$179.80
7 purchase totals =	$981.44		$1,077.8132	$1,077.81	$1,077.80	$1,077.90