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	$118.78	7.288%	$127.4367	$127.44	$127.45	$127.40
Purchase #2	$5.53	13.813%	$6.2939	$6.29	$6.30	$6.30
Purchase #3	$145.67	4.859%	$152.7481	$152.75	$152.75	$152.70
Purchase #4	$247.90	8.438%	$268.8178	$268.82	$268.80	$268.80
Purchase #5	$159.56	13.389%	$180.9235	$180.92	$180.90	$180.90
Purchase #6	$233.31	9.472%	$255.4091	$255.41	$255.40	$255.40
Purchase #7	$55.32	12.824%	$62.4142	$62.41	$62.40	$62.40
7 purchase totals =	$966.07		$1,054.0433	$1,054.04	$1,054.00	$1,053.90