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	$145.73	3.426%	$150.7227	$150.72	$150.70	$150.70
Purchase #2	$66.63	12.572%	$75.0067	$75.01	$75.00	$75.00
Purchase #3	$153.53	13.664%	$174.5083	$174.51	$174.50	$174.50
Purchase #4	$58.54	12.588%	$65.909	$65.91	$65.90	$65.90
Purchase #5	$217.25	12.448%	$244.2933	$244.29	$244.30	$244.30
Purchase #6	$189.80	13.449%	$215.3262	$215.33	$215.35	$215.30
Purchase #7	$112.89	12.700%	$127.227	$127.23	$127.25	$127.20
7 purchase totals =	$944.37		$1,052.9932	$1,053.00	$1,053.00	$1,052.90