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	$51.42	3.480%	$53.2094	$53.21	$53.20	$53.20
Purchase #2	$154.49	13.617%	$175.5269	$175.53	$175.55	$175.50
Purchase #3	$35.63	5.557%	$37.61	$37.61	$37.60	$37.60
Purchase #4	$182.67	9.557%	$200.1278	$200.13	$200.15	$200.10
Purchase #5	$238.62	8.821%	$259.6687	$259.67	$259.65	$259.70
Purchase #6	$245.71	9.104%	$268.0794	$268.08	$268.10	$268.10
Purchase #7	$56.64	8.869%	$61.6634	$61.66	$61.65	$61.70
7 purchase totals =	$965.18		$1,055.8856	$1,055.89	$1,055.90	$1,055.90