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	$142.89	4.143%	$148.8099	$148.81	$148.80	$148.80
Purchase #2	$171.81	3.594%	$177.9849	$177.98	$178.00	$178.00
Purchase #3	$185.56	3.142%	$191.3903	$191.39	$191.40	$191.40
Purchase #4	$232.51	11.565%	$259.3998	$259.40	$259.40	$259.40
Purchase #5	$223.72	7.663%	$240.8637	$240.86	$240.85	$240.90
Purchase #6	$59.74	7.258%	$64.0759	$64.08	$64.10	$64.10
Purchase #7	$93.62	10.874%	$103.8002	$103.80	$103.80	$103.80
7 purchase totals =	$1,109.85		$1,186.3247	$1,186.32	$1,186.35	$1,186.40