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	$237.80	10.190%	$262.0318	$262.03	$262.05	$262.00
Purchase #2	$168.82	7.289%	$181.1253	$181.13	$181.15	$181.10
Purchase #3	$118.94	8.404%	$128.9357	$128.94	$128.95	$128.90
Purchase #4	$212.81	5.127%	$223.7208	$223.72	$223.70	$223.70
Purchase #5	$112.99	6.262%	$120.0654	$120.07	$120.05	$120.10
Purchase #6	$28.78	10.764%	$31.8779	$31.88	$31.90	$31.90
Purchase #7	$161.76	11.624%	$180.563	$180.56	$180.55	$180.60
7 purchase totals =	$1,041.90		$1,128.3199	$1,128.33	$1,128.35	$1,128.30