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	$39.69	10.254%	$43.7598	$43.76	$43.75	$43.80
Purchase #2	$193.88	7.292%	$208.0177	$208.02	$208.00	$208.00
Purchase #3	$153.87	13.666%	$174.8979	$174.90	$174.90	$174.90
Purchase #4	$51.49	7.344%	$55.2714	$55.27	$55.25	$55.30
Purchase #5	$200.68	11.294%	$223.3448	$223.34	$223.35	$223.30
Purchase #6	$119.34	7.277%	$128.0244	$128.02	$128.00	$128.00
Purchase #7	$159.59	12.234%	$179.1142	$179.11	$179.10	$179.10
7 purchase totals =	$918.54		$1,012.4302	$1,012.42	$1,012.35	$1,012.40