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	$181.53	8.308%	$196.6115	$196.61	$196.60	$196.60
Purchase #2	$57.46	7.683%	$61.8747	$61.87	$61.85	$61.90
Purchase #3	$40.81	8.734%	$44.3743	$44.37	$44.35	$44.40
Purchase #4	$225.85	8.868%	$245.8784	$245.88	$245.90	$245.90
Purchase #5	$217.89	12.712%	$245.5882	$245.59	$245.60	$245.60
Purchase #6	$158.90	6.802%	$169.7084	$169.71	$169.70	$169.70
Purchase #7	$247.33	6.822%	$264.2029	$264.20	$264.20	$264.20
7 purchase totals =	$1,129.77		$1,228.2384	$1,228.23	$1,228.20	$1,228.30