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	$94.97	11.132%	$105.5421	$105.54	$105.55	$105.50
Purchase #2	$63.58	5.289%	$66.9427	$66.94	$66.95	$66.90
Purchase #3	$187.64	13.732%	$213.4067	$213.41	$213.40	$213.40
Purchase #4	$160.68	6.760%	$171.542	$171.54	$171.55	$171.50
Purchase #5	$229.74	5.837%	$243.1499	$243.15	$243.15	$243.10
Purchase #6	$162.51	4.276%	$169.4589	$169.46	$169.45	$169.50
Purchase #7	$75.36	3.571%	$78.0511	$78.05	$78.05	$78.10
7 purchase totals =	$974.48		$1,048.0934	$1,048.09	$1,048.10	$1,048.00