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	$194.71	7.357%	$209.0348	$209.03	$209.05	$209.00
Purchase #2	$33.29	13.630%	$37.8274	$37.83	$37.85	$37.80
Purchase #3	$62.36	3.332%	$64.4378	$64.44	$64.45	$64.40
Purchase #4	$202.84	12.585%	$228.3674	$228.37	$228.35	$228.40
Purchase #5	$242.50	7.650%	$261.0513	$261.05	$261.05	$261.10
Purchase #6	$139.37	13.621%	$158.3536	$158.35	$158.35	$158.40
Purchase #7	$209.48	6.148%	$222.3588	$222.36	$222.35	$222.40
7 purchase totals =	$1,084.55		$1,181.4311	$1,181.43	$1,181.45	$1,181.50