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	$196.98	8.437%	$213.5992	$213.60	$213.60	$213.60
Purchase #2	$175.69	7.787%	$189.371	$189.37	$189.35	$189.40
Purchase #3	$242.30	3.371%	$250.4679	$250.47	$250.45	$250.50
Purchase #4	$66.85	7.488%	$71.8557	$71.86	$71.85	$71.90
Purchase #5	$199.89	10.781%	$221.4401	$221.44	$221.45	$221.40
Purchase #6	$190.77	3.348%	$197.157	$197.16	$197.15	$197.20
Purchase #7	$238.48	9.265%	$260.5752	$260.58	$260.60	$260.60
7 purchase totals =	$1,310.96		$1,404.4661	$1,404.48	$1,404.45	$1,404.60