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	$180.36	7.596%	$194.0601	$194.06	$194.05	$194.10
Purchase #2	$198.71	13.539%	$225.6133	$225.61	$225.60	$225.60
Purchase #3	$193.32	13.379%	$219.1843	$219.18	$219.20	$219.20
Purchase #4	$129.71	5.309%	$136.5963	$136.60	$136.60	$136.60
Purchase #5	$150.31	3.695%	$155.864	$155.86	$155.85	$155.90
Purchase #6	$210.27	5.794%	$222.453	$222.45	$222.45	$222.50
Purchase #7	$31.83	5.398%	$33.5482	$33.55	$33.55	$33.50
7 purchase totals =	$1,094.51		$1,187.3192	$1,187.31	$1,187.30	$1,187.40