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	$31.76	10.319%	$35.0373	$35.04	$35.05	$35.00
Purchase #2	$5.85	10.329%	$6.4542	$6.45	$6.45	$6.50
Purchase #3	$221.84	3.637%	$229.9083	$229.91	$229.90	$229.90
Purchase #4	$248.29	8.862%	$270.2935	$270.29	$270.30	$270.30
Purchase #5	$226.27	10.182%	$249.3088	$249.31	$249.30	$249.30
Purchase #6	$88.67	4.342%	$92.5201	$92.52	$92.50	$92.50
Purchase #7	$151.93	8.481%	$164.8152	$164.82	$164.80	$164.80
7 purchase totals =	$974.61		$1,048.3374	$1,048.34	$1,048.30	$1,048.30