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	$118.40	10.214%	$130.4934	$130.49	$130.50	$130.50
Purchase #2	$114.49	13.801%	$130.2908	$130.29	$130.30	$130.30
Purchase #3	$135.99	4.550%	$142.1775	$142.18	$142.20	$142.20
Purchase #4	$55.32	6.766%	$59.063	$59.06	$59.05	$59.10
Purchase #5	$176.25	6.764%	$188.1716	$188.17	$188.15	$188.20
Purchase #6	$132.61	9.281%	$144.9175	$144.92	$144.90	$144.90
Purchase #7	$227.57	6.486%	$242.3302	$242.33	$242.35	$242.30
7 purchase totals =	$960.63		$1,037.4440	$1,037.44	$1,037.45	$1,037.50