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	$202.95	3.301%	$209.6494	$209.65	$209.65	$209.60
Purchase #2	$144.58	7.290%	$155.1199	$155.12	$155.10	$155.10
Purchase #3	$164.74	7.482%	$177.0658	$177.07	$177.05	$177.10
Purchase #4	$73.50	12.801%	$82.9087	$82.91	$82.90	$82.90
Purchase #5	$169.62	9.262%	$185.3302	$185.33	$185.35	$185.30
Purchase #6	$118.31	7.692%	$127.4104	$127.41	$127.40	$127.40
Purchase #7	$83.72	6.377%	$89.0588	$89.06	$89.05	$89.10
7 purchase totals =	$957.42		$1,026.5432	$1,026.55	$1,026.50	$1,026.50