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	$155.91	13.874%	$177.541	$177.54	$177.55	$177.50
Purchase #2	$81.59	5.280%	$85.898	$85.90	$85.90	$85.90
Purchase #3	$184.98	6.224%	$196.4932	$196.49	$196.50	$196.50
Purchase #4	$197.60	7.472%	$212.3647	$212.36	$212.35	$212.40
Purchase #5	$36.48	6.577%	$38.8793	$38.88	$38.90	$38.90
Purchase #6	$244.72	5.816%	$258.9529	$258.95	$258.95	$259.00
Purchase #7	$79.77	4.818%	$83.6133	$83.61	$83.60	$83.60
7 purchase totals =	$981.05		$1,053.7424	$1,053.73	$1,053.75	$1,053.80