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	$226.66	9.275%	$247.6827	$247.68	$247.70	$247.70
Purchase #2	$149.52	6.657%	$159.4735	$159.47	$159.45	$159.50
Purchase #3	$180.73	10.560%	$199.8151	$199.82	$199.80	$199.80
Purchase #4	$48.62	11.531%	$54.2264	$54.23	$54.25	$54.20
Purchase #5	$187.28	4.663%	$196.0129	$196.01	$196.00	$196.00
Purchase #6	$135.25	4.494%	$141.3281	$141.33	$141.35	$141.30
Purchase #7	$5.29	11.645%	$5.906	$5.91	$5.90	$5.90
7 purchase totals =	$933.35		$1,004.4447	$1,004.45	$1,004.45	$1,004.40