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	$192.30	9.263%	$210.1127	$210.11	$210.10	$210.10
Purchase #2	$81.68	10.107%	$89.9354	$89.94	$89.95	$89.90
Purchase #3	$142.54	6.592%	$151.9362	$151.94	$151.95	$151.90
Purchase #4	$42.47	3.313%	$43.877	$43.88	$43.90	$43.90
Purchase #5	$138.91	6.202%	$147.5252	$147.53	$147.55	$147.50
Purchase #6	$219.67	3.562%	$227.4946	$227.49	$227.50	$227.50
Purchase #7	$243.49	7.701%	$262.2412	$262.24	$262.25	$262.20
7 purchase totals =	$1,061.06		$1,133.1223	$1,133.13	$1,133.20	$1,133.00