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	$224.62	4.335%	$234.3573	$234.36	$234.35	$234.40
Purchase #2	$165.70	4.695%	$173.4796	$173.48	$173.50	$173.50
Purchase #3	$95.89	4.602%	$100.3029	$100.30	$100.30	$100.30
Purchase #4	$91.93	8.148%	$99.4205	$99.42	$99.40	$99.40
Purchase #5	$158.29	6.811%	$169.0711	$169.07	$169.05	$169.10
Purchase #6	$195.79	9.256%	$213.9123	$213.91	$213.90	$213.90
Purchase #7	$118.37	4.597%	$123.8115	$123.81	$123.80	$123.80
7 purchase totals =	$1,050.59		$1,114.3552	$1,114.35	$1,114.30	$1,114.40