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	$133.98	12.520%	$150.7543	$150.75	$150.75	$150.80
Purchase #2	$130.72	6.374%	$139.0521	$139.05	$139.05	$139.10
Purchase #3	$90.44	8.542%	$98.1654	$98.17	$98.15	$98.20
Purchase #4	$172.91	3.650%	$179.2212	$179.22	$179.20	$179.20
Purchase #5	$238.62	4.872%	$250.2456	$250.25	$250.25	$250.20
Purchase #6	$105.75	9.824%	$116.1389	$116.14	$116.15	$116.10
Purchase #7	$201.63	4.615%	$210.9352	$210.94	$210.95	$210.90
7 purchase totals =	$1,074.05		$1,144.5127	$1,144.52	$1,144.50	$1,144.50