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	$111.89	10.530%	$123.672	$123.67	$123.65	$123.70
Purchase #2	$235.60	6.681%	$251.3404	$251.34	$251.35	$251.30
Purchase #3	$98.34	13.790%	$111.9011	$111.90	$111.90	$111.90
Purchase #4	$89.29	12.343%	$100.3111	$100.31	$100.30	$100.30
Purchase #5	$193.93	3.312%	$200.353	$200.35	$200.35	$200.40
Purchase #6	$61.71	9.405%	$67.5138	$67.51	$67.50	$67.50
Purchase #7	$233.29	9.315%	$255.021	$255.02	$255.00	$255.00
7 purchase totals =	$1,024.05		$1,110.1124	$1,110.10	$1,110.05	$1,110.10