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	$42.64	10.457%	$47.0989	$47.10	$47.10	$47.10
Purchase #2	$180.72	4.423%	$188.7132	$188.71	$188.70	$188.70
Purchase #3	$184.80	6.484%	$196.7824	$196.78	$196.80	$196.80
Purchase #4	$14.83	13.228%	$16.7917	$16.79	$16.80	$16.80
Purchase #5	$79.76	11.814%	$89.1828	$89.18	$89.20	$89.20
Purchase #6	$36.54	9.777%	$40.1125	$40.11	$40.10	$40.10
Purchase #7	$148.67	3.410%	$153.7396	$153.74	$153.75	$153.70
7 purchase totals =	$687.96		$732.4211	$732.41	$732.45	$732.40