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	$145.31	4.655%	$152.0742	$152.07	$152.05	$152.10
Purchase #2	$140.47	7.377%	$150.8325	$150.83	$150.85	$150.80
Purchase #3	$242.43	3.519%	$250.9611	$250.96	$250.95	$251.00
Purchase #4	$198.46	8.448%	$215.2259	$215.23	$215.25	$215.20
Purchase #5	$52.47	12.651%	$59.108	$59.11	$59.10	$59.10
Purchase #6	$174.46	7.381%	$187.3369	$187.34	$187.35	$187.30
Purchase #7	$31.67	7.521%	$34.0519	$34.05	$34.05	$34.10
7 purchase totals =	$985.27		$1,049.5905	$1,049.59	$1,049.60	$1,049.60