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	$189.61	5.855%	$200.7117	$200.71	$200.70	$200.70
Purchase #2	$193.39	13.455%	$219.4106	$219.41	$219.40	$219.40
Purchase #3	$101.92	6.789%	$108.8393	$108.84	$108.85	$108.80
Purchase #4	$18.59	10.404%	$20.5241	$20.52	$20.50	$20.50
Purchase #5	$167.81	6.270%	$178.3317	$178.33	$178.35	$178.30
Purchase #6	$226.39	9.662%	$248.2638	$248.26	$248.25	$248.30
Purchase #7	$67.34	5.558%	$71.0828	$71.08	$71.10	$71.10
7 purchase totals =	$965.05		$1,047.1640	$1,047.15	$1,047.15	$1,047.10