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	$191.55	7.502%	$205.9201	$205.92	$205.90	$205.90
Purchase #2	$158.72	3.649%	$164.5117	$164.51	$164.50	$164.50
Purchase #3	$210.27	9.126%	$229.4592	$229.46	$229.45	$229.50
Purchase #4	$184.51	9.459%	$201.9628	$201.96	$201.95	$202.00
Purchase #5	$94.66	7.229%	$101.503	$101.50	$101.50	$101.50
Purchase #6	$41.26	6.145%	$43.7954	$43.80	$43.80	$43.80
Purchase #7	$89.61	10.482%	$99.0029	$99.00	$99.00	$99.00
7 purchase totals =	$970.58		$1,046.1551	$1,046.15	$1,046.10	$1,046.20