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	$80.52	9.834%	$88.4383	$88.44	$88.45	$88.40
Purchase #2	$186.38	5.384%	$196.4147	$196.41	$196.40	$196.40
Purchase #3	$105.77	12.836%	$119.3466	$119.35	$119.35	$119.30
Purchase #4	$40.68	7.401%	$43.6907	$43.69	$43.70	$43.70
Purchase #5	$216.55	4.257%	$225.7685	$225.77	$225.75	$225.80
Purchase #6	$223.80	12.498%	$251.7705	$251.77	$251.75	$251.80
Purchase #7	$195.69	11.573%	$218.3372	$218.34	$218.35	$218.30
7 purchase totals =	$1,049.39		$1,143.7665	$1,143.77	$1,143.75	$1,143.70