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	$183.36	6.202%	$194.732	$194.73	$194.75	$194.70
Purchase #2	$224.41	5.374%	$236.4698	$236.47	$236.45	$236.50
Purchase #3	$141.68	9.261%	$154.801	$154.80	$154.80	$154.80
Purchase #4	$172.34	9.197%	$188.1901	$188.19	$188.20	$188.20
Purchase #5	$85.49	5.855%	$90.4954	$90.50	$90.50	$90.50
Purchase #6	$186.71	7.366%	$200.4631	$200.46	$200.45	$200.50
Purchase #7	$43.77	6.542%	$46.6334	$46.63	$46.65	$46.60
7 purchase totals =	$1,037.76		$1,111.7848	$1,111.78	$1,111.80	$1,111.80